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Hydrogen Atom Reading course MAT394 “Partial Differential Equations”, Fall 2013 Franz Altea University of Toronto January 9, 2014 Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 1 / 37

Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

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Page 1: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Hydrogen AtomReading course MAT394 “Partial Differential Equations”,

Fall 2013

Franz Altea

University of Toronto

January 9, 2014

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 1 / 37

Page 2: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Table of contents

1 Schrodinger Equation

2 Separation of Variables

3 Position Solutions

4 Legendre Equations

5 Radial Equation

6 Endgame

7 References

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 2 / 37

Page 3: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Schrodinger Equation

Schrodinger Equation

i~∂Ψ(~r , t)

∂t= − ~2

2m∆Ψ(~r , t) + V (~r)Ψ(~r , t) (1)

where ~r = (ρ, ϕ,Θ) is the positional vector, and t is time,

V (~r) = − e2

4πε0

1

ρ(2)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 3 / 37

Page 4: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 1

let Ψ(~r , t) = Ψ(~r)T (t). Then (1) becomes:

i~Ψ(~r)T ′(t) = − ~2

2m∆Ψ(~r)T (t) + V (~r)Ψ(~r)T (t),

i~T ′(t)

T (t)=− ~2

2m∆Ψ(~r) + V (~r)Ψ(~r)

Ψ(~r).

Then LHS and RHS are constants. Let E = i~T ′(t)

T (t)

T (t) = ce−iE~ t (3)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 4 / 37

Page 5: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 1

let Ψ(~r , t) = Ψ(~r)T (t). Then (1) becomes:

i~Ψ(~r)T ′(t) = − ~2

2m∆Ψ(~r)T (t) + V (~r)Ψ(~r)T (t),

i~T ′(t)

T (t)=− ~2

2m∆Ψ(~r) + V (~r)Ψ(~r)

Ψ(~r).

Then LHS and RHS are constants. Let E = i~T ′(t)

T (t)

T (t) = ce−iE~ t (3)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 4 / 37

Page 6: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 1

let Ψ(~r , t) = Ψ(~r)T (t). Then (1) becomes:

i~Ψ(~r)T ′(t) = − ~2

2m∆Ψ(~r)T (t) + V (~r)Ψ(~r)T (t),

i~T ′(t)

T (t)=− ~2

2m∆Ψ(~r) + V (~r)Ψ(~r)

Ψ(~r).

Then LHS and RHS are constants. Let E = i~T ′(t)

T (t)

T (t) = ce−iE~ t (3)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 4 / 37

Page 7: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 1

let Ψ(~r , t) = Ψ(~r)T (t). Then (1) becomes:

i~Ψ(~r)T ′(t) = − ~2

2m∆Ψ(~r)T (t) + V (~r)Ψ(~r)T (t),

i~T ′(t)

T (t)=− ~2

2m∆Ψ(~r) + V (~r)Ψ(~r)

Ψ(~r).

Then LHS and RHS are constants. Let E = i~T ′(t)

T (t)

T (t) = ce−iE~ t (3)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 4 / 37

Page 8: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 2

(1) becomes Time Independent Schrodinger Equation:

− ~2

2m∆Ψ(~r) + V (~r)Ψ(~r) = EΨ(~r) (4)

Separate Variables Again. Let Ψ(~r) = P(ρ)Y (φ, θ)

∆ =∂2

∂ρ2+

2

ρ

∂ρ+

1

ρ2Λ,

Λ =1

sin(φ)

∂φ(sin(φ)

∂φ) +

1

sin2(φ)

∂2

∂θ2,

− ~2

2m(∂2

∂ρ2P(ρ)Y (φ, θ) +

2

ρ

∂ρP(ρ)Y (φ, θ) +

1

ρ2ΛY (φ, θ)P(ρ))+

V (~r)P(ρ)Y (φ, θ) = EP(ρ)Y (φ, θ)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 5 / 37

Page 9: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 2

(1) becomes Time Independent Schrodinger Equation:

− ~2

2m∆Ψ(~r) + V (~r)Ψ(~r) = EΨ(~r) (4)

Separate Variables Again. Let Ψ(~r) = P(ρ)Y (φ, θ)

∆ =∂2

∂ρ2+

2

ρ

∂ρ+

1

ρ2Λ,

Λ =1

sin(φ)

∂φ(sin(φ)

∂φ) +

1

sin2(φ)

∂2

∂θ2,

− ~2

2m(∂2

∂ρ2P(ρ)Y (φ, θ) +

2

ρ

∂ρP(ρ)Y (φ, θ) +

1

ρ2ΛY (φ, θ)P(ρ))+

V (~r)P(ρ)Y (φ, θ) = EP(ρ)Y (φ, θ)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 5 / 37

Page 10: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 2

(1) becomes Time Independent Schrodinger Equation:

− ~2

2m∆Ψ(~r) + V (~r)Ψ(~r) = EΨ(~r) (4)

Separate Variables Again. Let Ψ(~r) = P(ρ)Y (φ, θ)

∆ =∂2

∂ρ2+

2

ρ

∂ρ+

1

ρ2Λ,

Λ =1

sin(φ)

∂φ(sin(φ)

∂φ) +

1

sin2(φ)

∂2

∂θ2,

− ~2

2m(∂2

∂ρ2P(ρ)Y (φ, θ) +

2

ρ

∂ρP(ρ)Y (φ, θ) +

1

ρ2ΛY (φ, θ)P(ρ))+

V (~r)P(ρ)Y (φ, θ) = EP(ρ)Y (φ, θ)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 5 / 37

Page 11: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 2

(1) becomes Time Independent Schrodinger Equation:

− ~2

2m∆Ψ(~r) + V (~r)Ψ(~r) = EΨ(~r) (4)

Separate Variables Again. Let Ψ(~r) = P(ρ)Y (φ, θ)

∆ =∂2

∂ρ2+

2

ρ

∂ρ+

1

ρ2Λ,

Λ =1

sin(φ)

∂φ(sin(φ)

∂φ) +

1

sin2(φ)

∂2

∂θ2,

− ~2

2m(∂2

∂ρ2P(ρ)Y (φ, θ) +

2

ρ

∂ρP(ρ)Y (φ, θ) +

1

ρ2ΛY (φ, θ)P(ρ))+

V (~r)P(ρ)Y (φ, θ) = EP(ρ)Y (φ, θ)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 5 / 37

Page 12: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 2

− ~2

2m

(P ′′(ρ)

P(ρ)+

2

ρ

P ′(ρ)

P(ρ)+

1

ρ2

ΛY (φ, θ)

Y (φ, θ)

)+ V (~r)− E = 0,

~2

2m

(ρ2P ′′(ρ)

P(ρ)+ 2ρ

P ′(ρ)

P(ρ)

)+ E − V (ρ) = − ~2

2m

ΛY (φ, θ)

Y (φ, θ)(5)

LHS and RHS are just constants as they do not depend on any variable.

Let λ1 = −ΛY (φ, θ)

Y (φ, θ)

ΛY (φ, θ) = −Y (φ, θ)λ1

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 6 / 37

Page 13: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 2

− ~2

2m

(P ′′(ρ)

P(ρ)+

2

ρ

P ′(ρ)

P(ρ)+

1

ρ2

ΛY (φ, θ)

Y (φ, θ)

)+ V (~r)− E = 0,

~2

2m

(ρ2P ′′(ρ)

P(ρ)+ 2ρ

P ′(ρ)

P(ρ)

)+ E − V (ρ) = − ~2

2m

ΛY (φ, θ)

Y (φ, θ)(5)

LHS and RHS are just constants as they do not depend on any variable.

Let λ1 = −ΛY (φ, θ)

Y (φ, θ)

ΛY (φ, θ) = −Y (φ, θ)λ1

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 6 / 37

Page 14: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 2

− ~2

2m

(P ′′(ρ)

P(ρ)+

2

ρ

P ′(ρ)

P(ρ)+

1

ρ2

ΛY (φ, θ)

Y (φ, θ)

)+ V (~r)− E = 0,

~2

2m

(ρ2P ′′(ρ)

P(ρ)+ 2ρ

P ′(ρ)

P(ρ)

)+ E − V (ρ) = − ~2

2m

ΛY (φ, θ)

Y (φ, θ)(5)

LHS and RHS are just constants as they do not depend on any variable.

Let λ1 = −ΛY (φ, θ)

Y (φ, θ)

ΛY (φ, θ) = −Y (φ, θ)λ1

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 6 / 37

Page 15: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 2

− ~2

2m

(P ′′(ρ)

P(ρ)+

2

ρ

P ′(ρ)

P(ρ)+

1

ρ2

ΛY (φ, θ)

Y (φ, θ)

)+ V (~r)− E = 0,

~2

2m

(ρ2P ′′(ρ)

P(ρ)+ 2ρ

P ′(ρ)

P(ρ)

)+ E − V (ρ) = − ~2

2m

ΛY (φ, θ)

Y (φ, θ)(5)

LHS and RHS are just constants as they do not depend on any variable.

Let λ1 = −ΛY (φ, θ)

Y (φ, θ)

ΛY (φ, θ) = −Y (φ, θ)λ1

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 6 / 37

Page 16: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 2

− ~2

2m

(P ′′(ρ)

P(ρ)+

2

ρ

P ′(ρ)

P(ρ)+

1

ρ2

ΛY (φ, θ)

Y (φ, θ)

)+ V (~r)− E = 0,

~2

2m

(ρ2P ′′(ρ)

P(ρ)+ 2ρ

P ′(ρ)

P(ρ)

)+ E − V (ρ) = − ~2

2m

ΛY (φ, θ)

Y (φ, θ)(5)

LHS and RHS are just constants as they do not depend on any variable.

Let λ1 = −ΛY (φ, θ)

Y (φ, θ)

ΛY (φ, θ) = −Y (φ, θ)λ1

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 6 / 37

Page 17: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 3

Separate Variables once again. Let (φ, θ) = Φ(φ)Θ(θ)

(1

sin(φ)

∂φ(sin(φ)

∂Φ(φ)Θ(θ)

∂φ) +

1

sin2(φ)

∂2Φ(φ)Θ(θ)

∂θ2

)= −λ1Φ(φ)Θ(θ)

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) +

Θ′′(θ)

Θ(θ)= −λ1 sin2(φ)

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) + λ1 sin2(φ) = −Θ

′′(θ)

Θ(θ)

Once again, both sides are constants. Let −Θ′′(θ)

Θ(θ)= λ2

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 7 / 37

Page 18: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 3

Separate Variables once again. Let (φ, θ) = Φ(φ)Θ(θ)

(1

sin(φ)

∂φ(sin(φ)

∂Φ(φ)Θ(θ)

∂φ) +

1

sin2(φ)

∂2Φ(φ)Θ(θ)

∂θ2

)= −λ1Φ(φ)Θ(θ)

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) +

Θ′′(θ)

Θ(θ)= −λ1 sin2(φ)

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) + λ1 sin2(φ) = −Θ

′′(θ)

Θ(θ)

Once again, both sides are constants. Let −Θ′′(θ)

Θ(θ)= λ2

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 7 / 37

Page 19: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 3

Separate Variables once again. Let (φ, θ) = Φ(φ)Θ(θ)

(1

sin(φ)

∂φ(sin(φ)

∂Φ(φ)Θ(θ)

∂φ) +

1

sin2(φ)

∂2Φ(φ)Θ(θ)

∂θ2

)= −λ1Φ(φ)Θ(θ)

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) +

Θ′′(θ)

Θ(θ)= −λ1 sin2(φ)

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) + λ1 sin2(φ) = −Θ

′′(θ)

Θ(θ)

Once again, both sides are constants. Let −Θ′′(θ)

Θ(θ)= λ2

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 7 / 37

Page 20: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 3

Separate Variables once again. Let (φ, θ) = Φ(φ)Θ(θ)

(1

sin(φ)

∂φ(sin(φ)

∂Φ(φ)Θ(θ)

∂φ) +

1

sin2(φ)

∂2Φ(φ)Θ(θ)

∂θ2

)= −λ1Φ(φ)Θ(θ)

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) +

Θ′′(θ)

Θ(θ)= −λ1 sin2(φ)

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) + λ1 sin2(φ) = −Θ

′′(θ)

Θ(θ)

Once again, both sides are constants. Let −Θ′′(θ)

Θ(θ)= λ2

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 7 / 37

Page 21: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Separation of Variables

Separation of Variables 3

Separate Variables once again. Let (φ, θ) = Φ(φ)Θ(θ)

(1

sin(φ)

∂φ(sin(φ)

∂Φ(φ)Θ(θ)

∂φ) +

1

sin2(φ)

∂2Φ(φ)Θ(θ)

∂θ2

)= −λ1Φ(φ)Θ(θ)

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) +

Θ′′(θ)

Θ(θ)= −λ1 sin2(φ)

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) + λ1 sin2(φ) = −Θ

′′(θ)

Θ(θ)

Once again, both sides are constants. Let −Θ′′(θ)

Θ(θ)= λ2

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 7 / 37

Page 22: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Position Solutions Θ Equation

θ Equation

Θ′′(θ) = −λ2Θ(θ) with boundary condition Θ(0) = Θ(2π)

λ2 > 0 to get bounded solution because of BC. Let λ2 = m2

⇒ Θ(θ) = Ae imθ

Plug into Boundary Conditions:

A = Ae im2π

Hence mεZ

Θ(θ) = Ae imθ (6)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 8 / 37

Page 23: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Position Solutions Θ Equation

θ Equation

Θ′′(θ) = −λ2Θ(θ) with boundary condition Θ(0) = Θ(2π)λ2 > 0 to get bounded solution because of BC. Let λ2 = m2

⇒ Θ(θ) = Ae imθ

Plug into Boundary Conditions:

A = Ae im2π

Hence mεZ

Θ(θ) = Ae imθ (6)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 8 / 37

Page 24: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Position Solutions Θ Equation

θ Equation

Θ′′(θ) = −λ2Θ(θ) with boundary condition Θ(0) = Θ(2π)λ2 > 0 to get bounded solution because of BC. Let λ2 = m2

⇒ Θ(θ) = Ae imθ

Plug into Boundary Conditions:

A = Ae im2π

Hence mεZ

Θ(θ) = Ae imθ (6)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 8 / 37

Page 25: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Position Solutions Θ Equation

θ Equation

Θ′′(θ) = −λ2Θ(θ) with boundary condition Θ(0) = Θ(2π)λ2 > 0 to get bounded solution because of BC. Let λ2 = m2

⇒ Θ(θ) = Ae imθ

Plug into Boundary Conditions:

A = Ae im2π

Hence mεZ

Θ(θ) = Ae imθ (6)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 8 / 37

Page 26: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Position Solutions Θ Equation

θ Equation

Θ′′(θ) = −λ2Θ(θ) with boundary condition Θ(0) = Θ(2π)λ2 > 0 to get bounded solution because of BC. Let λ2 = m2

⇒ Θ(θ) = Ae imθ

Plug into Boundary Conditions:

A = Ae im2π

Hence mεZ

Θ(θ) = Ae imθ (6)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 8 / 37

Page 27: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Position Solutions Θ Equation

θ Equation

Θ′′(θ) = −λ2Θ(θ) with boundary condition Θ(0) = Θ(2π)λ2 > 0 to get bounded solution because of BC. Let λ2 = m2

⇒ Θ(θ) = Ae imθ

Plug into Boundary Conditions:

A = Ae im2π

Hence mεZ

Θ(θ) = Ae imθ (6)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 8 / 37

Page 28: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Position Solutions Φ Equation

φ Equation

From (5), plug in m

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) + λ1 sin2(φ) = m2,mεZ

sin(φ)d

dφ(sin(φ)Φ′(φ)) + (λ1 sin2(φ)−m2)Φ(φ) = 0

Solution is Legendre Polynomials. Let x = cos(φ)

dx = −sin(φ)dφ⇒ dφ = − dx√1− x2

−(1− x2)d

dx(−(1− x2)Φ′(x)) + (λ1(1− x2)−m2)Φ(x) = 0

d

dx((1− x2)

dx) + (λ1 −

m2

1− x2)Φ = 0 (7)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 9 / 37

Page 29: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Position Solutions Φ Equation

φ Equation

From (5), plug in m

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) + λ1 sin2(φ) = m2,mεZ

sin(φ)d

dφ(sin(φ)Φ′(φ)) + (λ1 sin2(φ)−m2)Φ(φ) = 0

Solution is Legendre Polynomials. Let x = cos(φ)

dx = −sin(φ)dφ⇒ dφ = − dx√1− x2

−(1− x2)d

dx(−(1− x2)Φ′(x)) + (λ1(1− x2)−m2)Φ(x) = 0

d

dx((1− x2)

dx) + (λ1 −

m2

1− x2)Φ = 0 (7)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 9 / 37

Page 30: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Position Solutions Φ Equation

φ Equation

From (5), plug in m

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) + λ1 sin2(φ) = m2,mεZ

sin(φ)d

dφ(sin(φ)Φ′(φ)) + (λ1 sin2(φ)−m2)Φ(φ) = 0

Solution is Legendre Polynomials. Let x = cos(φ)

dx = −sin(φ)dφ⇒ dφ = − dx√1− x2

−(1− x2)d

dx(−(1− x2)Φ′(x)) + (λ1(1− x2)−m2)Φ(x) = 0

d

dx((1− x2)

dx) + (λ1 −

m2

1− x2)Φ = 0 (7)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 9 / 37

Page 31: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Position Solutions Φ Equation

φ Equation

From (5), plug in m

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) + λ1 sin2(φ) = m2,mεZ

sin(φ)d

dφ(sin(φ)Φ′(φ)) + (λ1 sin2(φ)−m2)Φ(φ) = 0

Solution is Legendre Polynomials. Let x = cos(φ)

dx = −sin(φ)dφ⇒ dφ = − dx√1− x2

−(1− x2)d

dx(−(1− x2)Φ′(x)) + (λ1(1− x2)−m2)Φ(x) = 0

d

dx((1− x2)

dx) + (λ1 −

m2

1− x2)Φ = 0 (7)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 9 / 37

Page 32: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Position Solutions Φ Equation

φ Equation

From (5), plug in m

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) + λ1 sin2(φ) = m2,mεZ

sin(φ)d

dφ(sin(φ)Φ′(φ)) + (λ1 sin2(φ)−m2)Φ(φ) = 0

Solution is Legendre Polynomials. Let x = cos(φ)

dx = −sin(φ)dφ⇒ dφ = − dx√1− x2

−(1− x2)d

dx(−(1− x2)Φ′(x)) + (λ1(1− x2)−m2)Φ(x) = 0

d

dx((1− x2)

dx) + (λ1 −

m2

1− x2)Φ = 0 (7)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 9 / 37

Page 33: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Position Solutions Φ Equation

φ Equation

From (5), plug in m

sin(φ)

Φ(φ)

d

dφ(sin(φ)Φ′(φ)) + λ1 sin2(φ) = m2,mεZ

sin(φ)d

dφ(sin(φ)Φ′(φ)) + (λ1 sin2(φ)−m2)Φ(φ) = 0

Solution is Legendre Polynomials. Let x = cos(φ)

dx = −sin(φ)dφ⇒ dφ = − dx√1− x2

−(1− x2)d

dx(−(1− x2)Φ′(x)) + (λ1(1− x2)−m2)Φ(x) = 0

d

dx((1− x2)

dx) + (λ1 −

m2

1− x2)Φ = 0 (7)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 9 / 37

Page 34: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Legendre Polynomials

Legendre Polynomials

Consider this equation:

d

dx((1− x2)f ′(x)) + λ1f (x) = 0

(1− x2)f ′′(x)− 2xf ′(x) + λ1f (x) = 0

Let f (x) =∞∑j=0

ajxj

f ′(x) =∞∑j=0

jajxj−1

f ′′(x) =∞∑j=0

j(j − 1)ajxj−2

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 10 / 37

Page 35: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Legendre Polynomials

Legendre Polynomials

Consider this equation:

d

dx((1− x2)f ′(x)) + λ1f (x) = 0

(1− x2)f ′′(x)− 2xf ′(x) + λ1f (x) = 0

Let f (x) =∞∑j=0

ajxj

f ′(x) =∞∑j=0

jajxj−1

f ′′(x) =∞∑j=0

j(j − 1)ajxj−2

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 10 / 37

Page 36: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Legendre Polynomials

Legendre Polynomials

Consider this equation:

d

dx((1− x2)f ′(x)) + λ1f (x) = 0

(1− x2)f ′′(x)− 2xf ′(x) + λ1f (x) = 0

Let f (x) =∞∑j=0

ajxj

f ′(x) =∞∑j=0

jajxj−1

f ′′(x) =∞∑j=0

j(j − 1)ajxj−2

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 10 / 37

Page 37: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Legendre Polynomials

Legendre Polynomials

Consider this equation:

d

dx((1− x2)f ′(x)) + λ1f (x) = 0

(1− x2)f ′′(x)− 2xf ′(x) + λ1f (x) = 0

Let f (x) =∞∑j=0

ajxj

f ′(x) =∞∑j=0

jajxj−1

f ′′(x) =∞∑j=0

j(j − 1)ajxj−2

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 10 / 37

Page 38: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Legendre Polynomials

Legendre Polynomials

∞∑j=0

j(j − 1)ajxj−2 −

∞∑j=0

j(j − 1)ajxj − 2

∞∑j=0

jajxj + λ1

∞∑j=0

ajxj = 0

∞∑j=0

(j + 2)(j + 1)aj+2xj +

∞∑j=0

(−j(j + 1) + λ1)ajxj = 0

If we match the coefficients of the equation, we get:

(j + 2)(j + 1)aj+2 − (−j(j + 1) + λ1)aj = 0

aj+2 =j(j + 1)− λ1

(j + 2)(j + 1)aj (8)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 11 / 37

Page 39: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Legendre Polynomials

Legendre Polynomials

∞∑j=0

j(j − 1)ajxj−2 −

∞∑j=0

j(j − 1)ajxj − 2

∞∑j=0

jajxj + λ1

∞∑j=0

ajxj = 0

∞∑j=0

(j + 2)(j + 1)aj+2xj +

∞∑j=0

(−j(j + 1) + λ1)ajxj = 0

If we match the coefficients of the equation, we get:

(j + 2)(j + 1)aj+2 − (−j(j + 1) + λ1)aj = 0

aj+2 =j(j + 1)− λ1

(j + 2)(j + 1)aj (8)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 11 / 37

Page 40: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Legendre Polynomials

Legendre Polynomials

∞∑j=0

j(j − 1)ajxj−2 −

∞∑j=0

j(j − 1)ajxj − 2

∞∑j=0

jajxj + λ1

∞∑j=0

ajxj = 0

∞∑j=0

(j + 2)(j + 1)aj+2xj +

∞∑j=0

(−j(j + 1) + λ1)ajxj = 0

If we match the coefficients of the equation, we get:

(j + 2)(j + 1)aj+2 − (−j(j + 1) + λ1)aj = 0

aj+2 =j(j + 1)− λ1

(j + 2)(j + 1)aj (8)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 11 / 37

Page 41: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Legendre Polynomials

Legendre Polynomials

∞∑j=0

j(j − 1)ajxj−2 −

∞∑j=0

j(j − 1)ajxj − 2

∞∑j=0

jajxj + λ1

∞∑j=0

ajxj = 0

∞∑j=0

(j + 2)(j + 1)aj+2xj +

∞∑j=0

(−j(j + 1) + λ1)ajxj = 0

If we match the coefficients of the equation, we get:

(j + 2)(j + 1)aj+2 − (−j(j + 1) + λ1)aj = 0

aj+2 =j(j + 1)− λ1

(j + 2)(j + 1)aj (8)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 11 / 37

Page 42: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Legendre Polynomials

Legendre Polynomials

Since, we want it to be analytic, we need limk→∞ aj = 0. For that, weneed to have the series terminate at some jmax such that ajmax+1 = 0. Letjmax = k

0 =k(k + 1)− λ1

(k + 2)(k + 1)ak

λ1 = k(k + 1)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 12 / 37

Page 43: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Legendre Polynomials

Legendre Polynomials

Since, we want it to be analytic, we need limk→∞ aj = 0. For that, weneed to have the series terminate at some jmax such that ajmax+1 = 0. Letjmax = k

0 =k(k + 1)− λ1

(k + 2)(k + 1)ak

λ1 = k(k + 1)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 12 / 37

Page 44: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Legendre Polynomials

Legendre Polynomials

Since, we want it to be analytic, we need limk→∞ aj = 0. For that, weneed to have the series terminate at some jmax such that ajmax+1 = 0. Letjmax = k

0 =k(k + 1)− λ1

(k + 2)(k + 1)ak

λ1 = k(k + 1)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 12 / 37

Page 45: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Rodrigues’ Formula

Rodrigues’ Formula

If we take a0 = 1, then solution to fk(x) is:

fk(x) =1

2kk!

dk

dxk(x2 − 1)k (9)

Proof.

Consider g(x) = (x2 − 1)n

g ′(x) = 2nx(x2 − 1)n−1 = 2nxg(x)

x2 − 1

2nxg(x)− (x2 − 1)g ′(x) = 0

2ng(x) + 2(n − 1)xg ′(x)− (x2 − 1)g ′′(x) = 0

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 13 / 37

Page 46: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Rodrigues’ Formula

Rodrigues’ Formula

If we take a0 = 1, then solution to fk(x) is:

fk(x) =1

2kk!

dk

dxk(x2 − 1)k (9)

Proof.

Consider g(x) = (x2 − 1)n

g ′(x) = 2nx(x2 − 1)n−1 = 2nxg(x)

x2 − 1

2nxg(x)− (x2 − 1)g ′(x) = 0

2ng(x) + 2(n − 1)xg ′(x)− (x2 − 1)g ′′(x) = 0

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 13 / 37

Page 47: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Rodrigues’ Formula

Rodrigues’ Formula

If we take a0 = 1, then solution to fk(x) is:

fk(x) =1

2kk!

dk

dxk(x2 − 1)k (9)

Proof.

Consider g(x) = (x2 − 1)n

g ′(x) = 2nx(x2 − 1)n−1 = 2nxg(x)

x2 − 1

2nxg(x)− (x2 − 1)g ′(x) = 0

2ng(x) + 2(n − 1)xg ′(x)− (x2 − 1)g ′′(x) = 0

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 13 / 37

Page 48: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Rodrigues’ Formula

Rodrigues’ Formula

If we take a0 = 1, then solution to fk(x) is:

fk(x) =1

2kk!

dk

dxk(x2 − 1)k (9)

Proof.

Consider g(x) = (x2 − 1)n

g ′(x) = 2nx(x2 − 1)n−1 = 2nxg(x)

x2 − 1

2nxg(x)− (x2 − 1)g ′(x) = 0

2ng(x) + 2(n − 1)xg ′(x)− (x2 − 1)g ′′(x) = 0

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 13 / 37

Page 49: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Rodrigues’ Formula

Rodrigues’ Formula

If we take a0 = 1, then solution to fk(x) is:

fk(x) =1

2kk!

dk

dxk(x2 − 1)k (9)

Proof.

Consider g(x) = (x2 − 1)n

g ′(x) = 2nx(x2 − 1)n−1 = 2nxg(x)

x2 − 1

2nxg(x)− (x2 − 1)g ′(x) = 0

2ng(x) + 2(n − 1)xg ′(x)− (x2 − 1)g ′′(x) = 0

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 13 / 37

Page 50: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Rodrigues’ Formula

Rodrigue’s Formula

Proof(continued).

Using Leibniz Formula and applying derivative n times:

dn

dxnA(x)B(x) =

n∑k=0

n!

k!(n − k)!

dkA

dxkdn−kB

dxn−k.

First term becomes: 2ng (n)

Second term becomes: 2(n − 1)xg (n+1) + 2n(n − 1)g (n)

Third term becomes: −(x2 − 1)g (n+2)(x)− n2xg (n+1) − n(n − 1)

22g (n)(x)

Hence, we get:

(1− x2)g (n+2)(x) +−2xg (n+1) + n(n + 1)g (n) = 0

Hence g (n) satisfies Legendre’s Equation

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 14 / 37

Page 51: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Rodrigues’ Formula

Rodrigue’s Formula

Proof(continued).

Using Leibniz Formula and applying derivative n times:

dn

dxnA(x)B(x) =

n∑k=0

n!

k!(n − k)!

dkA

dxkdn−kB

dxn−k.

First term becomes: 2ng (n)

Second term becomes: 2(n − 1)xg (n+1) + 2n(n − 1)g (n)

Third term becomes: −(x2 − 1)g (n+2)(x)− n2xg (n+1) − n(n − 1)

22g (n)(x)

Hence, we get:

(1− x2)g (n+2)(x) +−2xg (n+1) + n(n + 1)g (n) = 0

Hence g (n) satisfies Legendre’s Equation

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 14 / 37

Page 52: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Rodrigues’ Formula

Rodrigue’s Formula

Proof(continued).

Using Leibniz Formula and applying derivative n times:

dn

dxnA(x)B(x) =

n∑k=0

n!

k!(n − k)!

dkA

dxkdn−kB

dxn−k.

First term becomes: 2ng (n)

Second term becomes: 2(n − 1)xg (n+1) + 2n(n − 1)g (n)

Third term becomes: −(x2 − 1)g (n+2)(x)− n2xg (n+1) − n(n − 1)

22g (n)(x)

Hence, we get:

(1− x2)g (n+2)(x) +−2xg (n+1) + n(n + 1)g (n) = 0

Hence g (n) satisfies Legendre’s Equation

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 14 / 37

Page 53: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Rodrigues’ Formula

Rodrigue’s Formula

Proof(continued).

Using Leibniz Formula and applying derivative n times:

dn

dxnA(x)B(x) =

n∑k=0

n!

k!(n − k)!

dkA

dxkdn−kB

dxn−k.

First term becomes: 2ng (n)

Second term becomes: 2(n − 1)xg (n+1) + 2n(n − 1)g (n)

Third term becomes: −(x2 − 1)g (n+2)(x)− n2xg (n+1) − n(n − 1)

22g (n)(x)

Hence, we get:

(1− x2)g (n+2)(x) +−2xg (n+1) + n(n + 1)g (n) = 0

Hence g (n) satisfies Legendre’s Equation

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 14 / 37

Page 54: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Rodrigues’ Formula

Rodrigue’s Formula

Proof(continued).

Using Leibniz Formula and applying derivative n times:

dn

dxnA(x)B(x) =

n∑k=0

n!

k!(n − k)!

dkA

dxkdn−kB

dxn−k.

First term becomes: 2ng (n)

Second term becomes: 2(n − 1)xg (n+1) + 2n(n − 1)g (n)

Third term becomes: −(x2 − 1)g (n+2)(x)− n2xg (n+1) − n(n − 1)

22g (n)(x)

Hence, we get:

(1− x2)g (n+2)(x) +−2xg (n+1) + n(n + 1)g (n) = 0

Hence g (n) satisfies Legendre’s Equation

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 14 / 37

Page 55: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Associated Legendre Equation

Associated Legendre Equation

Going back to hydrogen atom, from (7):

d

dx((1− x2)

dx) + (λ1 −

m2

1− x2)Φ = 0

(1− x2)d2Φ

dx2− 2x

dx+ (λ1 −

|m|2

1− x2)Φ = 0

Let Φ = (1− x2)|m|

2 f (x)

dx= |m| x(1− x2)

|m|2−1f (x) + (1− x2)

|m|2 f ′(x)

d2Φ

dx2= (1− x2)

|m|2 f ′′(x)− 2 |m| |x(1− x2)

|m|2−1f (x)

+ (− |m| (1− x2)|m|

2−1 + |m| (|m| − 2)(1− x2)

|m|2−2)f (x)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 15 / 37

Page 56: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Associated Legendre Equation

Associated Legendre Equation

Going back to hydrogen atom, from (7):

d

dx((1− x2)

dx) + (λ1 −

m2

1− x2)Φ = 0

(1− x2)d2Φ

dx2− 2x

dx+ (λ1 −

|m|2

1− x2)Φ = 0

Let Φ = (1− x2)|m|

2 f (x)

dx= |m| x(1− x2)

|m|2−1f (x) + (1− x2)

|m|2 f ′(x)

d2Φ

dx2= (1− x2)

|m|2 f ′′(x)− 2 |m| |x(1− x2)

|m|2−1f (x)

+ (− |m| (1− x2)|m|

2−1 + |m| (|m| − 2)(1− x2)

|m|2−2)f (x)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 15 / 37

Page 57: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Associated Legendre Equation

Associated Legendre Equation

Going back to hydrogen atom, from (7):

d

dx((1− x2)

dx) + (λ1 −

m2

1− x2)Φ = 0

(1− x2)d2Φ

dx2− 2x

dx+ (λ1 −

|m|2

1− x2)Φ = 0

Let Φ = (1− x2)|m|

2 f (x)

dx= |m| x(1− x2)

|m|2−1f (x) + (1− x2)

|m|2 f ′(x)

d2Φ

dx2= (1− x2)

|m|2 f ′′(x)− 2 |m| |x(1− x2)

|m|2−1f (x)

+ (− |m| (1− x2)|m|

2−1 + |m| (|m| − 2)(1− x2)

|m|2−2)f (x)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 15 / 37

Page 58: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Associated Legendre Equation

Associated Legendre Equation

Going back to hydrogen atom, from (7):

d

dx((1− x2)

dx) + (λ1 −

m2

1− x2)Φ = 0

(1− x2)d2Φ

dx2− 2x

dx+ (λ1 −

|m|2

1− x2)Φ = 0

Let Φ = (1− x2)|m|

2 f (x)

dx= |m| x(1− x2)

|m|2−1f (x) + (1− x2)

|m|2 f ′(x)

d2Φ

dx2= (1− x2)

|m|2 f ′′(x)− 2 |m| |x(1− x2)

|m|2−1f (x)

+ (− |m| (1− x2)|m|

2−1 + |m| (|m| − 2)(1− x2)

|m|2−2)f (x)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 15 / 37

Page 59: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Associated Legendre Equation

Associated Legendre Equation

Plugging it into the equation:

(1− x2)f ′′ + 2(|m|+ 1)xf ′(x) + (λ1 − |m| (|m|+ 1)) = 0 (10)

Do power series expansion. Let f (x) =∞∑j=0

ajxj

∞∑j=0

(j + 2)(j + 1)aj+2xj −

∞∑j=0

[j(j − 1 + 2 |m|+ 2)

− (λ1 − |m| (|m|+ 1)))]ajxj = 0

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 16 / 37

Page 60: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Associated Legendre Equation

Associated Legendre Equation

Plugging it into the equation:

(1− x2)f ′′ + 2(|m|+ 1)xf ′(x) + (λ1 − |m| (|m|+ 1)) = 0 (10)

Do power series expansion. Let f (x) =∞∑j=0

ajxj

∞∑j=0

(j + 2)(j + 1)aj+2xj −

∞∑j=0

[j(j − 1 + 2 |m|+ 2)

− (λ1 − |m| (|m|+ 1)))]ajxj = 0

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 16 / 37

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Legendre Equations Associated Legendre Equation

Associated Legendre Equation

Plugging it into the equation:

(1− x2)f ′′ + 2(|m|+ 1)xf ′(x) + (λ1 − |m| (|m|+ 1)) = 0 (10)

Do power series expansion. Let f (x) =∞∑j=0

ajxj

∞∑j=0

(j + 2)(j + 1)aj+2xj −

∞∑j=0

[j(j − 1 + 2 |m|+ 2)

− (λ1 − |m| (|m|+ 1)))]ajxj = 0

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 16 / 37

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Legendre Equations Associated Legendre Equation

Associated Lagguere Equation

aj+2 =j(j + 2 |m|+ 1)− (λ1 − |m| (|m|+ 1))

(j + 2)(j + 1)aj (11)

∃jmax = k s.t. ak+1 = 0 as we want limj→∞

aj = 0 as we want series to

converge and we want f to be analytic.

k(k + 2 |m|+ 1) = λ1 − |m| (|m|+ 1)

λ1 = (k + |m|)(k + |m|+ 1)

Let ` = k + |m|λ1 = `(`+ 1)

Since k ≥ 0⇒ |m| ≤ ` and `εZ+

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 17 / 37

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Legendre Equations Associated Legendre Equation

Associated Lagguere Equation

aj+2 =j(j + 2 |m|+ 1)− (λ1 − |m| (|m|+ 1))

(j + 2)(j + 1)aj (11)

∃jmax = k s.t. ak+1 = 0 as we want limj→∞

aj = 0 as we want series to

converge and we want f to be analytic.

k(k + 2 |m|+ 1) = λ1 − |m| (|m|+ 1)

λ1 = (k + |m|)(k + |m|+ 1)

Let ` = k + |m|λ1 = `(`+ 1)

Since k ≥ 0⇒ |m| ≤ ` and `εZ+

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 17 / 37

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Legendre Equations Associated Legendre Equation

Associated Lagguere Equation

aj+2 =j(j + 2 |m|+ 1)− (λ1 − |m| (|m|+ 1))

(j + 2)(j + 1)aj (11)

∃jmax = k s.t. ak+1 = 0 as we want limj→∞

aj = 0 as we want series to

converge and we want f to be analytic.

k(k + 2 |m|+ 1) = λ1 − |m| (|m|+ 1)

λ1 = (k + |m|)(k + |m|+ 1)

Let ` = k + |m|λ1 = `(`+ 1)

Since k ≥ 0⇒ |m| ≤ ` and `εZ+

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 17 / 37

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Legendre Equations Associated Legendre Equation

Associated Lagguere Equation

aj+2 =j(j + 2 |m|+ 1)− (λ1 − |m| (|m|+ 1))

(j + 2)(j + 1)aj (11)

∃jmax = k s.t. ak+1 = 0 as we want limj→∞

aj = 0 as we want series to

converge and we want f to be analytic.

k(k + 2 |m|+ 1) = λ1 − |m| (|m|+ 1)

λ1 = (k + |m|)(k + |m|+ 1)

Let ` = k + |m|

λ1 = `(`+ 1)

Since k ≥ 0⇒ |m| ≤ ` and `εZ+

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 17 / 37

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Legendre Equations Associated Legendre Equation

Associated Lagguere Equation

aj+2 =j(j + 2 |m|+ 1)− (λ1 − |m| (|m|+ 1))

(j + 2)(j + 1)aj (11)

∃jmax = k s.t. ak+1 = 0 as we want limj→∞

aj = 0 as we want series to

converge and we want f to be analytic.

k(k + 2 |m|+ 1) = λ1 − |m| (|m|+ 1)

λ1 = (k + |m|)(k + |m|+ 1)

Let ` = k + |m|λ1 = `(`+ 1)

Since k ≥ 0⇒ |m| ≤ ` and `εZ+

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 17 / 37

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Legendre Equations Associated Legendre Equation

Associated Lagguere Equation

aj+2 =j(j + 2 |m|+ 1)− (λ1 − |m| (|m|+ 1))

(j + 2)(j + 1)aj (11)

∃jmax = k s.t. ak+1 = 0 as we want limj→∞

aj = 0 as we want series to

converge and we want f to be analytic.

k(k + 2 |m|+ 1) = λ1 − |m| (|m|+ 1)

λ1 = (k + |m|)(k + |m|+ 1)

Let ` = k + |m|λ1 = `(`+ 1)

Since k ≥ 0⇒ |m| ≤ ` and `εZ+

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 17 / 37

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Legendre Equations Rodrigue’s Formula for ALE

Rodrigues’ Formula for ALE

Ψ(φ) = Pm` (x) where x = cos(φ)

Pm` (x) = (1− x2)

|m|2

1

2``!

d`+|m|

dx`+|m|(x2 − 1)` (12)

Proof.

From Rodrigues’ Formula, g(x) =1

2``!

d`

dx`(x2 − 1)` satisfies

(1− x2)g ′′(x)− 2xg ′(x) + `(`+ 1)g(x)Taking |m| derivatives of it

(1− x2)g (|m+2|)(x)− 2(|m|+ 1)xg (|m+1|)(x)

+ (`(`+ 1)− |m| (|m|+ 1))g (|m|)(x) = 0

Hence, g (|m|)(x) satisfies (10)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 18 / 37

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Legendre Equations Rodrigue’s Formula for ALE

Rodrigues’ Formula for ALE

Ψ(φ) = Pm` (x) where x = cos(φ)

Pm` (x) = (1− x2)

|m|2

1

2``!

d`+|m|

dx`+|m|(x2 − 1)` (12)

Proof.

From Rodrigues’ Formula, g(x) =1

2``!

d`

dx`(x2 − 1)` satisfies

(1− x2)g ′′(x)− 2xg ′(x) + `(`+ 1)g(x)

Taking |m| derivatives of it

(1− x2)g (|m+2|)(x)− 2(|m|+ 1)xg (|m+1|)(x)

+ (`(`+ 1)− |m| (|m|+ 1))g (|m|)(x) = 0

Hence, g (|m|)(x) satisfies (10)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 18 / 37

Page 70: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Legendre Equations Rodrigue’s Formula for ALE

Rodrigues’ Formula for ALE

Ψ(φ) = Pm` (x) where x = cos(φ)

Pm` (x) = (1− x2)

|m|2

1

2``!

d`+|m|

dx`+|m|(x2 − 1)` (12)

Proof.

From Rodrigues’ Formula, g(x) =1

2``!

d`

dx`(x2 − 1)` satisfies

(1− x2)g ′′(x)− 2xg ′(x) + `(`+ 1)g(x)Taking |m| derivatives of it

(1− x2)g (|m+2|)(x)− 2(|m|+ 1)xg (|m+1|)(x)

+ (`(`+ 1)− |m| (|m|+ 1))g (|m|)(x) = 0

Hence, g (|m|)(x) satisfies (10)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 18 / 37

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Legendre Equations Φ Solution

φ solution

Solution to Φ eigenfunction is

Φ`,m(φ) = Pm` (cosφ) (13)

where mεZ, `εZ+ and |m| ≤ `And Pm

` (cosφ) is given by (12)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 19 / 37

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Radial Equation Substitution

Radial Equation

Going back to Radial Equation and plugging in values for eigenvalues:

ρ2P ′′(ρ) + 2ρP ′(ρ) + (E − V )2mρ2

~2P(ρ) = `(`+ 1)P(ρ) (14)

Substitute u(ρ) = ρP(ρ)

P ′(ρ) =u′ρ− u

ρ2

P ′′(ρ) =u′′ρ− 2u′ + 2u

ρ2

~2

2mu′′(ρ) +

(~2`(`+ 1)

2mρ2+ V (ρ)

)u(ρ) = Eu(ρ)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 20 / 37

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Radial Equation Substitution

Radial Equation

Going back to Radial Equation and plugging in values for eigenvalues:

ρ2P ′′(ρ) + 2ρP ′(ρ) + (E − V )2mρ2

~2P(ρ) = `(`+ 1)P(ρ) (14)

Substitute u(ρ) = ρP(ρ)

P ′(ρ) =u′ρ− u

ρ2

P ′′(ρ) =u′′ρ− 2u′ + 2u

ρ2

~2

2mu′′(ρ) +

(~2`(`+ 1)

2mρ2+ V (ρ)

)u(ρ) = Eu(ρ)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 20 / 37

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Radial Equation Substitution

Radial Equation

Going back to Radial Equation and plugging in values for eigenvalues:

ρ2P ′′(ρ) + 2ρP ′(ρ) + (E − V )2mρ2

~2P(ρ) = `(`+ 1)P(ρ) (14)

Substitute u(ρ) = ρP(ρ)

P ′(ρ) =u′ρ− u

ρ2

P ′′(ρ) =u′′ρ− 2u′ + 2u

ρ2

~2

2mu′′(ρ) +

(~2`(`+ 1)

2mρ2+ V (ρ)

)u(ρ) = Eu(ρ)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 20 / 37

Page 75: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Radial Equation Substitution

Radial Equation

Going back to Radial Equation and plugging in values for eigenvalues:

ρ2P ′′(ρ) + 2ρP ′(ρ) + (E − V )2mρ2

~2P(ρ) = `(`+ 1)P(ρ) (14)

Substitute u(ρ) = ρP(ρ)

P ′(ρ) =u′ρ− u

ρ2

P ′′(ρ) =u′′ρ− 2u′ + 2u

ρ2

~2

2mu′′(ρ) +

(~2`(`+ 1)

2mρ2+ V (ρ)

)u(ρ) = Eu(ρ)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 20 / 37

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Radial Equation Substitution

Radial Equation

We are looking for bound states so E < 0

let k =

√−2mE

~Plug in k and potential equation from (2)

u′′(ρ)

k2−(`(`+ 1)

k2ρ2− 2m

k2~2

e2

4πε0ρ

)u(ρ) = u(ρ)

Let ρ0 =me2

2πε0~2kand r = kρ and w(r) = u(ρ)

w ′(r) = ku′(ρ)⇒ w ′′(r) = k2u′′(ρ)

w ′′(r) =

(1− ρ0

r+`(`+ 1)

r2

)w(r) (15)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 21 / 37

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Radial Equation Substitution

Radial Equation

We are looking for bound states so E < 0

let k =

√−2mE

~Plug in k and potential equation from (2)

u′′(ρ)

k2−(`(`+ 1)

k2ρ2− 2m

k2~2

e2

4πε0ρ

)u(ρ) = u(ρ)

Let ρ0 =me2

2πε0~2kand r = kρ and w(r) = u(ρ)

w ′(r) = ku′(ρ)⇒ w ′′(r) = k2u′′(ρ)

w ′′(r) =

(1− ρ0

r+`(`+ 1)

r2

)w(r) (15)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 21 / 37

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Radial Equation Substitution

Radial Equation

We are looking for bound states so E < 0

let k =

√−2mE

~Plug in k and potential equation from (2)

u′′(ρ)

k2−(`(`+ 1)

k2ρ2− 2m

k2~2

e2

4πε0ρ

)u(ρ) = u(ρ)

Let ρ0 =me2

2πε0~2kand r = kρ and w(r) = u(ρ)

w ′(r) = ku′(ρ)⇒ w ′′(r) = k2u′′(ρ)

w ′′(r) =

(1− ρ0

r+`(`+ 1)

r2

)w(r) (15)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 21 / 37

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Radial Equation Substitution

Radial Equation

We are looking for bound states so E < 0

let k =

√−2mE

~Plug in k and potential equation from (2)

u′′(ρ)

k2−(`(`+ 1)

k2ρ2− 2m

k2~2

e2

4πε0ρ

)u(ρ) = u(ρ)

Let ρ0 =me2

2πε0~2kand r = kρ and w(r) = u(ρ)

w ′(r) = ku′(ρ)⇒ w ′′(r) = k2u′′(ρ)

w ′′(r) =

(1− ρ0

r+`(`+ 1)

r2

)w(r) (15)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 21 / 37

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Radial Equation Substitution

Radial Equation

We are looking for bound states so E < 0

let k =

√−2mE

~Plug in k and potential equation from (2)

u′′(ρ)

k2−(`(`+ 1)

k2ρ2− 2m

k2~2

e2

4πε0ρ

)u(ρ) = u(ρ)

Let ρ0 =me2

2πε0~2kand r = kρ and w(r) = u(ρ)

w ′(r) = ku′(ρ)⇒ w ′′(r) = k2u′′(ρ)

w ′′(r) =

(1− ρ0

r+`(`+ 1)

r2

)w(r) (15)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 21 / 37

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Radial Equation Substitution

Radial Equation

As r →∞, (15) becomes:

w ′′(r) = w(r)

w(r) = e±r

But we want limr→∞ w = 0. Hence we throw away e+r . As r → 0, (15)becomes:

w ′′(r) =`(`+ 1)

r2w(r)

This is a Euler Equation, so let w(r) = r j

j(j − 1) = `(`+ 1)

j = −` or j = `+ 1

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 22 / 37

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Radial Equation Substitution

Radial Equation

As r →∞, (15) becomes:

w ′′(r) = w(r)

w(r) = e±r

But we want limr→∞ w = 0. Hence we throw away e+r . As r → 0, (15)becomes:

w ′′(r) =`(`+ 1)

r2w(r)

This is a Euler Equation, so let w(r) = r j

j(j − 1) = `(`+ 1)

j = −` or j = `+ 1

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 22 / 37

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Radial Equation Substitution

Radial Equation

As r →∞, (15) becomes:

w ′′(r) = w(r)

w(r) = e±r

But we want limr→∞ w = 0. Hence we throw away e+r . As r → 0, (15)becomes:

w ′′(r) =`(`+ 1)

r2w(r)

This is a Euler Equation, so let w(r) = r j

j(j − 1) = `(`+ 1)

j = −` or j = `+ 1

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 22 / 37

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Radial Equation Substitution

Radial Equation

As r →∞, (15) becomes:

w ′′(r) = w(r)

w(r) = e±r

But we want limr→∞ w = 0. Hence we throw away e+r . As r → 0, (15)becomes:

w ′′(r) =`(`+ 1)

r2w(r)

This is a Euler Equation, so let w(r) = r j

j(j − 1) = `(`+ 1)

j = −` or j = `+ 1

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 22 / 37

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Radial Equation Substitution

Radial Equation

As r →∞, (15) becomes:

w ′′(r) = w(r)

w(r) = e±r

But we want limr→∞ w = 0. Hence we throw away e+r . As r → 0, (15)becomes:

w ′′(r) =`(`+ 1)

r2w(r)

This is a Euler Equation, so let w(r) = r j

j(j − 1) = `(`+ 1)

j = −` or j = `+ 1

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 22 / 37

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Radial Equation Substitution

Radial Equation

We throw out j = −` as it would diverge as r → 0

w(r) = r `+1

To get rid of asymptotic solution,we want solution of this form:

w(r) = r `+1e−rv(r)

w ′(r) = (`+ 1)r `e−rv(r)− r `+1e−rv(r) + r `+1e−rv(r)

w ′′(r) = r `e−r[(−2`− 2 + r

`(`+ 1)

r

)v(r) + 2(`+ 1− r)v ′(r) + rv ′′(r)

]

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 23 / 37

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Radial Equation Substitution

Radial Equation

We throw out j = −` as it would diverge as r → 0

w(r) = r `+1

To get rid of asymptotic solution,we want solution of this form:

w(r) = r `+1e−rv(r)

w ′(r) = (`+ 1)r `e−rv(r)− r `+1e−rv(r) + r `+1e−rv(r)

w ′′(r) = r `e−r[(−2`− 2 + r

`(`+ 1)

r

)v(r) + 2(`+ 1− r)v ′(r) + rv ′′(r)

]

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 23 / 37

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Radial Equation Substitution

Radial Equation

We throw out j = −` as it would diverge as r → 0

w(r) = r `+1

To get rid of asymptotic solution,we want solution of this form:

w(r) = r `+1e−rv(r)

w ′(r) = (`+ 1)r `e−rv(r)− r `+1e−rv(r) + r `+1e−rv(r)

w ′′(r) = r `e−r[(−2`− 2 + r

`(`+ 1)

r

)v(r) + 2(`+ 1− r)v ′(r) + rv ′′(r)

]

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 23 / 37

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Radial Equation Substitution

Radial Equation

(15) becomes:

r `e−r[(−2`− 2 + r

`(`+ 1)

r

)v(r) + 2(`+ 1− r)v ′(r) + rv ′′(r)

]=

(1− ρ0

r+`(`+ 1)

r2

)r `+1e−rv(r)

rv ′′(r) + 2(`+ 1− r)v ′(r) + (ρ0 − 2(`+ 1))v(r) = 0 (16)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 24 / 37

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Radial Equation Substitution

Radial Equation

(15) becomes:

r `e−r[(−2`− 2 + r

`(`+ 1)

r

)v(r) + 2(`+ 1− r)v ′(r) + rv ′′(r)

]=

(1− ρ0

r+`(`+ 1)

r2

)r `+1e−rv(r)

rv ′′(r) + 2(`+ 1− r)v ′(r) + (ρ0 − 2(`+ 1))v(r) = 0 (16)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 24 / 37

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Radial Equation Series Equation

Series Equation

Expand v(r) as power series: v(r) =∞∑j=0

cj rj

v ′(r) =∞∑j=0

jcj rj−1

v ′′(r) =∞∑j=0

j(j − 1)cj rj−2

(16) becomes:

∞∑j=0

(j + 1)(j)cj+1rj +

∞∑j=0

2(`+ 1)(j + 1)cj+1rj +

∞∑j=0

2jcj rj

+∞∑j=0

(−2`− 2 + ρ0)cj rj = 0

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 25 / 37

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Radial Equation Series Equation

Series Equation

Expand v(r) as power series: v(r) =∞∑j=0

cj rj

v ′(r) =∞∑j=0

jcj rj−1

v ′′(r) =∞∑j=0

j(j − 1)cj rj−2

(16) becomes:

∞∑j=0

(j + 1)(j)cj+1rj +

∞∑j=0

2(`+ 1)(j + 1)cj+1rj +

∞∑j=0

2jcj rj

+∞∑j=0

(−2`− 2 + ρ0)cj rj = 0

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 25 / 37

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Radial Equation Series Equation

Series Equation

Expand v(r) as power series: v(r) =∞∑j=0

cj rj

v ′(r) =∞∑j=0

jcj rj−1

v ′′(r) =∞∑j=0

j(j − 1)cj rj−2

(16) becomes:

∞∑j=0

(j + 1)(j)cj+1rj +

∞∑j=0

2(`+ 1)(j + 1)cj+1rj +

∞∑j=0

2jcj rj

+∞∑j=0

(−2`− 2 + ρ0)cj rj = 0

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 25 / 37

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Radial Equation Series Equation

Series Equation

cj+1 =2(`+ 1 + j)− ρ0

(j + 1)(j + 2`+ 2)cj (17)

As j →∞, (17) becomes: cj+1 ≈2

j + 1cj .

Let c0 = 1

cj+1 =2j+1

(j + 1)!

v(r) = e2r

and w(r) = r l+1er which we don’t want

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 26 / 37

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Radial Equation Series Equation

Series Equation

cj+1 =2(`+ 1 + j)− ρ0

(j + 1)(j + 2`+ 2)cj (17)

As j →∞, (17) becomes: cj+1 ≈2

j + 1cj .

Let c0 = 1

cj+1 =2j+1

(j + 1)!

v(r) = e2r

and w(r) = r l+1er which we don’t want

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 26 / 37

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Radial Equation Series Equation

Series Equation

cj+1 =2(`+ 1 + j)− ρ0

(j + 1)(j + 2`+ 2)cj (17)

As j →∞, (17) becomes: cj+1 ≈2

j + 1cj .

Let c0 = 1

cj+1 =2j+1

(j + 1)!

v(r) = e2r

and w(r) = r l+1er which we don’t want

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 26 / 37

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Radial Equation Series Equation

Series Equation

cj+1 =2(`+ 1 + j)− ρ0

(j + 1)(j + 2`+ 2)cj (17)

As j →∞, (17) becomes: cj+1 ≈2

j + 1cj .

Let c0 = 1

cj+1 =2j+1

(j + 1)!

v(r) = e2r

and w(r) = r l+1er which we don’t want

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 26 / 37

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Radial Equation Series Equation

Series Equation

cj+1 =2(`+ 1 + j)− ρ0

(j + 1)(j + 2`+ 2)cj (17)

As j →∞, (17) becomes: cj+1 ≈2

j + 1cj .

Let c0 = 1

cj+1 =2j+1

(j + 1)!

v(r) = e2r

and w(r) = r l+1er which we don’t want

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 26 / 37

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Radial Equation Series Equation

Series Equation

cj+1 =2(`+ 1 + j)− ρ0

(j + 1)(j + 2`+ 2)cj (17)

As j →∞, (17) becomes: cj+1 ≈2

j + 1cj .

Let c0 = 1

cj+1 =2j+1

(j + 1)!

v(r) = e2r

and w(r) = r l+1er which we don’t want

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 26 / 37

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Radial Equation Series Equation

Series Equation

Hence, series has to terminate. ∃jmax > 0, cjmax+1 = 0(17) becomes:

0 = 2(`+ 1 + jmax)− ρ0

let n = `+ 1 + jmax , nεN and ` ≤ n − 1

ρ0 = 2n =me2

2πε0~2

1

k(18)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 27 / 37

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Radial Equation Series Equation

Series Equation

Hence, series has to terminate. ∃jmax > 0, cjmax+1 = 0(17) becomes:

0 = 2(`+ 1 + jmax)− ρ0

let n = `+ 1 + jmax , nεN and ` ≤ n − 1

ρ0 = 2n =me2

2πε0~2

1

k(18)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 27 / 37

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Radial Equation Series Equation

Series Equation

Hence, series has to terminate. ∃jmax > 0, cjmax+1 = 0(17) becomes:

0 = 2(`+ 1 + jmax)− ρ0

let n = `+ 1 + jmax , nεN and ` ≤ n − 1

ρ0 = 2n =me2

2πε0~2

1

k(18)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 27 / 37

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Radial Equation Energy Eigenvalue

Energy Eigenvalue

k =me2

4πε0~2

1

n=

1

a1n=

~√−2mE

a1 =4πε0~2

me2= 0.529× 10−10m (19)

a1 is known as Bohr Radius

En = − 1

n2

m

2~2

(e2

4πε0

)2

for nεN

En =E1

n2(20)

which satisfies Bohr Energy

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 28 / 37

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Radial Equation Energy Eigenvalue

Energy Eigenvalue

k =me2

4πε0~2

1

n=

1

a1n=

~√−2mE

a1 =4πε0~2

me2= 0.529× 10−10m (19)

a1 is known as Bohr Radius

En = − 1

n2

m

2~2

(e2

4πε0

)2

for nεN

En =E1

n2(20)

which satisfies Bohr Energy

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 28 / 37

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Radial Equation Energy Eigenvalue

Energy Eigenvalue

k =me2

4πε0~2

1

n=

1

a1n=

~√−2mE

a1 =4πε0~2

me2= 0.529× 10−10m (19)

a1 is known as Bohr Radius

En = − 1

n2

m

2~2

(e2

4πε0

)2

for nεN

En =E1

n2(20)

which satisfies Bohr Energy

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 28 / 37

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Radial Equation Energy Eigenvalue

Energy Eigenvalue

k =me2

4πε0~2

1

n=

1

a1n=

~√−2mE

a1 =4πε0~2

me2= 0.529× 10−10m (19)

a1 is known as Bohr Radius

En = − 1

n2

m

2~2

(e2

4πε0

)2

for nεN

En =E1

n2(20)

which satisfies Bohr Energy

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 28 / 37

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Radial Equation Associated Lagguere Polynomials

Associated Lagguere Polynomials

Considerxy ′′ + (p + 1− x)y ′ + qy = 0

let y(x) =∑j≥0

ajxj

aj+1 =j − q

(j + 1)(j + p + 1)aj

let there be jmax , s.t. ajmax+1 = 0

0 = (jmax − q)ajmax

jmax = q

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 29 / 37

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Radial Equation Associated Lagguere Polynomials

Associated Lagguere Polynomials

Considerxy ′′ + (p + 1− x)y ′ + qy = 0

let y(x) =∑j≥0

ajxj

aj+1 =j − q

(j + 1)(j + p + 1)aj

let there be jmax , s.t. ajmax+1 = 0

0 = (jmax − q)ajmax

jmax = q

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 29 / 37

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Radial Equation Associated Lagguere Polynomials

Associated Lagguere Polynomials

Considerxy ′′ + (p + 1− x)y ′ + qy = 0

let y(x) =∑j≥0

ajxj

aj+1 =j − q

(j + 1)(j + p + 1)aj

let there be jmax , s.t. ajmax+1 = 0

0 = (jmax − q)ajmax

jmax = q

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 29 / 37

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Radial Equation Associated Lagguere Polynomials

Associated Lagguere Polynomials

Considerxy ′′ + (p + 1− x)y ′ + qy = 0

let y(x) =∑j≥0

ajxj

aj+1 =j − q

(j + 1)(j + p + 1)aj

let there be jmax , s.t. ajmax+1 = 0

0 = (jmax − q)ajmax

jmax = q

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 29 / 37

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Radial Equation Associated Lagguere Polynomials

Associated Lagguere Polynomials

Considerxy ′′ + (p + 1− x)y ′ + qy = 0

let y(x) =∑j≥0

ajxj

aj+1 =j − q

(j + 1)(j + p + 1)aj

let there be jmax , s.t. ajmax+1 = 0

0 = (jmax − q)ajmax

jmax = q

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 29 / 37

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Radial Equation Associated Lagguere Polynomials

Associated Lagguere Polynomials

Claim: aj =(−1)j(p + q)!

(q − j)!(p + j)!j!=

(q + p

q − j

)1

j!

Proof.

aj+1 =(−1)j+1(p + q)!

(q − j − 1)!(p + j + 1)!(j + 1)!

aj+1 =j − q

(j + 1)(j + p + 1)aj

Hence, y(x) =

q∑j=0

(q + p

q − j

)x j

j!

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 30 / 37

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Radial Equation Associated Lagguere Polynomials

Associated Lagguere Polynomials

Claim: aj =(−1)j(p + q)!

(q − j)!(p + j)!j!=

(q + p

q − j

)1

j!

Proof.

aj+1 =(−1)j+1(p + q)!

(q − j − 1)!(p + j + 1)!(j + 1)!

aj+1 =j − q

(j + 1)(j + p + 1)aj

Hence, y(x) =

q∑j=0

(q + p

q − j

)x j

j!

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 30 / 37

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Radial Equation Associated Lagguere Polynomials

Associated Lagguere Polynomials

Claim: aj =(−1)j(p + q)!

(q − j)!(p + j)!j!=

(q + p

q − j

)1

j!

Proof.

aj+1 =(−1)j+1(p + q)!

(q − j − 1)!(p + j + 1)!(j + 1)!

aj+1 =j − q

(j + 1)(j + p + 1)aj

Hence, y(x) =

q∑j=0

(q + p

q − j

)x j

j!

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 30 / 37

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Radial Equation Radial Solution

Radial Solution

Combining (16) and (18) we get:

rv ′′(r) + 2(`+ 1− r)v ′(r) + 2(n − (`+ 1))v(r) = 0

let x = 2r and L(x) = L(2r) = v(r)

xL′′(x) + (2(`+ 1)− x)L′(x) + (n − `− 1)L(x) = 0

v(r) = L2`+1n−`−1(2r) (21)

L2`+1n−`−1(2r) =

n−`−1∑j=0

(`+ n

j − 2`− 1

)(−1)j

j!2j r j (22)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 31 / 37

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Radial Equation Radial Solution

Radial Solution

Combining (16) and (18) we get:

rv ′′(r) + 2(`+ 1− r)v ′(r) + 2(n − (`+ 1))v(r) = 0

let x = 2r and L(x) = L(2r) = v(r)

xL′′(x) + (2(`+ 1)− x)L′(x) + (n − `− 1)L(x) = 0

v(r) = L2`+1n−`−1(2r) (21)

L2`+1n−`−1(2r) =

n−`−1∑j=0

(`+ n

j − 2`− 1

)(−1)j

j!2j r j (22)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 31 / 37

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Radial Equation Radial Solution

Radial Solution

Combining (16) and (18) we get:

rv ′′(r) + 2(`+ 1− r)v ′(r) + 2(n − (`+ 1))v(r) = 0

let x = 2r and L(x) = L(2r) = v(r)

xL′′(x) + (2(`+ 1)− x)L′(x) + (n − `− 1)L(x) = 0

v(r) = L2`+1n−`−1(2r) (21)

L2`+1n−`−1(2r) =

n−`−1∑j=0

(`+ n

j − 2`− 1

)(−1)j

j!2j r j (22)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 31 / 37

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Radial Equation Radial Solution

Radial Solution

Combining (16) and (18) we get:

rv ′′(r) + 2(`+ 1− r)v ′(r) + 2(n − (`+ 1))v(r) = 0

let x = 2r and L(x) = L(2r) = v(r)

xL′′(x) + (2(`+ 1)− x)L′(x) + (n − `− 1)L(x) = 0

v(r) = L2`+1n−`−1(2r) (21)

L2`+1n−`−1(2r) =

n−`−1∑j=0

(`+ n

j − 2`− 1

)(−1)j

j!2j r j (22)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 31 / 37

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Radial Equation Radial Solution

Radial Solution

Using (19) for k

P(ρ) =1

ρ

na1

)`+1

e− ρ

na1 v(ρ

na1)

P(ρ) =1

ρ

na1

)`+1

e− ρ

na1 L2`+1n−`−1(

na1) (23)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 32 / 37

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Radial Equation Radial Solution

Radial Solution

Using (19) for k

P(ρ) =1

ρ

na1

)`+1

e− ρ

na1 v(ρ

na1)

P(ρ) =1

ρ

na1

)`+1

e− ρ

na1 L2`+1n−`−1(

na1) (23)

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 32 / 37

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Endgame Eigenfunctions

Eigenfunctions

Ψ`,m,n = P`,n(p)Y`,m(φ, θ)Tn(t)

Taking eigenfunctions from (3), (6), (13), and (23)

Ψ`,m,n(r , φ, θ, t) = c1

ρ

na1

)`+1

e− ρ

na1 L2`+1n−`−1(

na1)Pm

` (cos θ)e imφe−iE1n2~

t

(24)with n εN, ` εZ+, m εZ and n-1 ≥ ` ≥ |m| and c is normalization constant

Note: Not considering spin, ` has 2`+ 1 degrees of freedom or degeneracy

and n hasn−1∑`=0

(2`+ 1) = n2 degrees of freedom

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 33 / 37

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Endgame Eigenfunctions

Eigenfunctions

Ψ`,m,n = P`,n(p)Y`,m(φ, θ)Tn(t)

Taking eigenfunctions from (3), (6), (13), and (23)

Ψ`,m,n(r , φ, θ, t) = c1

ρ

na1

)`+1

e− ρ

na1 L2`+1n−`−1(

na1)Pm

` (cos θ)e imφe−iE1n2~

t

(24)with n εN, ` εZ+, m εZ and n-1 ≥ ` ≥ |m| and c is normalization constant

Note: Not considering spin, ` has 2`+ 1 degrees of freedom or degeneracy

and n hasn−1∑`=0

(2`+ 1) = n2 degrees of freedom

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 33 / 37

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Endgame Eigenfunctions

Eigenfunctions

Ψ`,m,n = P`,n(p)Y`,m(φ, θ)Tn(t)

Taking eigenfunctions from (3), (6), (13), and (23)

Ψ`,m,n(r , φ, θ, t) = c1

ρ

na1

)`+1

e− ρ

na1 L2`+1n−`−1(

na1)Pm

` (cos θ)e imφe−iE1n2~

t

(24)with n εN, ` εZ+, m εZ and n-1 ≥ ` ≥ |m| and c is normalization constant

Note: Not considering spin, ` has 2`+ 1 degrees of freedom or degeneracy

and n hasn−1∑`=0

(2`+ 1) = n2 degrees of freedom

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 33 / 37

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Endgame Eigenfunctions

Eigenfunctions

Ψ`,m,n = P`,n(p)Y`,m(φ, θ)Tn(t)

Taking eigenfunctions from (3), (6), (13), and (23)

Ψ`,m,n(r , φ, θ, t) = c1

ρ

na1

)`+1

e− ρ

na1 L2`+1n−`−1(

na1)Pm

` (cos θ)e imφe−iE1n2~

t

(24)with n εN, ` εZ+, m εZ and n-1 ≥ ` ≥ |m| and c is normalization constant

Note: Not considering spin, ` has 2`+ 1 degrees of freedom or degeneracy

and n hasn−1∑`=0

(2`+ 1) = n2 degrees of freedom

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 33 / 37

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Endgame Example

Example

n = 1 ⇒ ` = 0 and m = 0

Pn=1,`=0(ρ) =e− ρ

a1

a1

Φ(φ) = 1

Ψn=1,`=0,m=0 =c

a1e− ρ

a1− iE1

~ t

∫∫∫|Ψ |2 dV = 1

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 34 / 37

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Endgame Example

Example

n = 1 ⇒ ` = 0 and m = 0

Pn=1,`=0(ρ) =e− ρ

a1

a1

Φ(φ) = 1

Ψn=1,`=0,m=0 =c

a1e− ρ

a1− iE1

~ t

∫∫∫|Ψ |2 dV = 1

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 34 / 37

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Endgame Example

Example

n = 1 ⇒ ` = 0 and m = 0

Pn=1,`=0(ρ) =e− ρ

a1

a1

Φ(φ) = 1

Ψn=1,`=0,m=0 =c

a1e− ρ

a1− iE1

~ t

∫∫∫|Ψ |2 dV = 1

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 34 / 37

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Endgame Example

Example

n = 1 ⇒ ` = 0 and m = 0

Pn=1,`=0(ρ) =e− ρ

a1

a1

Φ(φ) = 1

Ψn=1,`=0,m=0 =c

a1e− ρ

a1− iE1

~ t

∫∫∫|Ψ |2 dV = 1

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 34 / 37

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Endgame Example

Example

∫∫∫c2

a21

e− 2ρ

a1 dV = 1

c2

∞∫0

e− 2ρ

a1 ρ2dρ = a21

c =2√a1

Ψ =2

a132

e− ρ

a1− iE1

~ t

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 35 / 37

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Endgame Example

Example

∫∫∫c2

a21

e− 2ρ

a1 dV = 1

c2

∞∫0

e− 2ρ

a1 ρ2dρ = a21

c =2√a1

Ψ =2

a132

e− ρ

a1− iE1

~ t

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 35 / 37

Page 131: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Endgame Example

Example

∫∫∫c2

a21

e− 2ρ

a1 dV = 1

c2

∞∫0

e− 2ρ

a1 ρ2dρ = a21

c =2√a1

Ψ =2

a132

e− ρ

a1− iE1

~ t

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 35 / 37

Page 132: Hydrogen Atom [5pt] Reading course MAT394 ``Partial ... · Hydrogen Atom Reading course MAT394 \Partial Di erential Equations", Fall 2013 Franz Altea University of Toronto January

Endgame Example

Example

∫∫∫c2

a21

e− 2ρ

a1 dV = 1

c2

∞∫0

e− 2ρ

a1 ρ2dρ = a21

c =2√a1

Ψ =2

a132

e− ρ

a1− iE1

~ t

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 35 / 37

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Endgame General Solution

General Solution

Ψ`,m,n =∞∑

|m|≤`<n=1

cn,`,m1

ρ

na1

)`+1

e− ρ

na1 L2`+1n−`−1(

na1)Pm

` (cos θ)e imφe−iE1n2~

t

(25)where `εZ+ and mεZ

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 36 / 37

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References

References

Griffith, David. (2005). Introduction to Quantum Mechanics SecondEdition. USA: Pearson Education, Inc.

Lund, Metthe. (2000). Legendre polynomials and Rodrigue’s formula.Retrieved Dec 20,2013, fromhttp://www.nbi.dk/ polesen/borel/node4.html

Culham, J.R. Legendre Polynomials and Functions. Retrieved Dec20,2013, fromhttp://www.mhtlab.uwaterloo.ca/courses/me755/web chap5.pdf

Legendre Polynomials. Wikipedia. Retrieved Dec 20, 2013, fromhttp://en.wikipedia.org/wiki/Legendre polynomials

Laguerre polynomials.Wikipedia. Retrived Dec 20, 2013, fromhttp://en.wikipedia.org/wiki/Laguerre polynomials

Franz Altea (University of Toronto) Hydrogen Atom January 9, 2014 37 / 37