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Dynamical mean field theory: In practice. N.S.Vidhyadhiraja Theoretical sciences unit, JNCASR, Bangalore. Outline. Brief review of DMFT Impurity solvers Iterated perturbation theory Self energy calculation Symmetric case Asymmetric case - PowerPoint PPT Presentation
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Dynamical mean field theory: In practice
N.S.Vidhyadhiraja
Theoretical sciences unit,
JNCASR, Bangalore.
Outline
• Brief review of DMFT
• Impurity solvers
• Iterated perturbation theory
• Self energy calculation– Symmetric case– Asymmetric case
• Output – Green’s functions, DOS, Transport and thermodynamics
• Numerical implementation
Dynamical mean field theoryImplementation
∑(z)
Impurity solvers
• Iterated perturbation theory (IPT)
• Local moment approach
• Non-crossing approximation
• Exact diagonalization
• Quantum Monte Carlo
• Numerical Renormalization group
• Density-Matrix Renormalization group.
Iterated perturbation Theory (IPT)
• Iterated perturbation theory at half-filling: Self-energy is just the second order correction built out of Hartree propagators.
References for IPT:
• Green’s functions G(ω)• Spectral function A(ω)= -Im(G(ω))/π Electronic density of states• Re(G-1(ω))=0 gives Quasiparticle energies.• Z=[{1 - ∂(Re(∑))/∂ω)}ω 0]-1 is the quasiparticle
weight and Z-1 is the mass renormalization.
Physical observables
Transport Quantities
• Linear response – Kubo formula
Find the current-current correlation function.
• Optical Conductivity
• DC Conductivity = ω 0 limit of Optical Conductivity.
Numerical implementation