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Very large-scale computations of the free energies of eight low-lying structures of arginine in the gas phase. Robert J. Gdanitz NC A&T State University. 5 canonical (neutral) and 3 zwitterionic structures. C1. C2. C3. C4. C5. Z1. Z2. Z3. C1. C2. C3. C4. C5. Z1. Z2. Z3. - PowerPoint PPT Presentation
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Very large-scale Very large-scale computations of the free computations of the free
energies ofenergies of eight low-lying eight low-lying structures of structures of argininearginine in the in the
gas phasegas phase
Robert J. GdanitzRobert J. Gdanitz
NC A&T State UniversityNC A&T State University
5 canonical (neutral) and 5 canonical (neutral) and 3 zwitterionic structures3 zwitterionic structures
C1 C2 C3 C4
C5 Z1 Z2 Z3
C1 C2
C3 C4
C5 Z1
Z2 Z3
TheoryTheory
Electronic SchrElectronic Schrödinger equationödinger equation::
Hamiltonian:Hamiltonian:
Constraint #2: Pauli principle:Constraint #2: Pauli principle:
Constraint #1: Spin symmetryConstraint #1: Spin symmetry
AlgebraizationAlgebraization
““Configuration Interaction” Configuration Interaction” (CI):(CI):
Slater determinants:Slater determinants:
Orbitals:Orbitals:
ApproximationApproximationBasisBasis setset
full-CIfull-CI
Approximation of full-CIApproximation of full-CI
Perturbation theory:Perturbation theory:
Coupled-Cluster:Coupled-Cluster:
Extrapolation to basis set limitExtrapolation to basis set limit
Independent particle contribution:Independent particle contribution:
Singlet pairs:Singlet pairs:
Triplet pairs:Triplet pairs:
Computers & Software Computers & Software (PNNL)(PNNL)
NWMpp1: 512-node IBM SP (retired)NWMpp1: 512-node IBM SP (retired)
NWMpp2: 1960-processor HP/LinuxNWMpp2: 1960-processor HP/Linux
NWChem, PNNLNWChem, PNNL
MP2/QZ and CCSD(T)/DZ:MP2/QZ and CCSD(T)/DZ:128 proc./48 GBytes of NWMpp1128 proc./48 GBytes of NWMpp1 for 2 daysfor 2 days
Energy w/r/t C5Energy w/r/t C5
-1
0
1
2
3
4
5
6
7
8
9
10
HF/DZ
~ TZ~ Q
Z
~ (DTQ)
HF/DZ + M
P2/DZ
~ TZ~ Q
Z
HF/TZ + MP2/(D
T)Z
HF/QZ + M
P2/(TQ)Z
HF/(DTQ)Z
+ MP2/(T
Q)Z
~ (x+1/2)-3
HF/(DTQ)Z
+ MP2/(T
Q)Z + C
CSD/DZ
~ + CCSD[T
]/DZ
~ CCSD(T
)/DZ
E [kcal/mol]
C1
C2
C3
C4
C5
Z1
Z2
Z3
The WinnersThe Winners
C3C3
CC55
G = 0.4 kcal/molG = 0.4 kcal/mol
ThanksThanks
Wim Cardoen, UtahWim Cardoen, Utah
Robert Harrison, Oak Ridge Nat’l LabRobert Harrison, Oak Ridge Nat’l Lab
Bert de Jong, PNNLBert de Jong, PNNL
Anita Orendt, UtahAnita Orendt, Utah
Jack Simons, Utah Jack Simons, Utah
Piotr Skurski, Gdansk, PolandPiotr Skurski, Gdansk, Poland
Theresa Windus, PNNLTheresa Windus, PNNL
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