Application of the unitary group approach (UGA) to evaluate spin
density for Configuration Interaction (CI) calculations in a basis
of S$^{2}$ eigenfunctions
density for Configuration Interaction (CI) calculations in a basis
of S$^{2}$ eigenfunctions
File(s)
Author(s)
Polyak, I
Bearpark, MJ
Robb, MA
Type
Journal Article
Abstract
We present an implementation of the spin-dependent unitary group approach
to calculate spin densities for CI calculations in a basis of spin
symmetry-adapted functions. Using S$^{2}$ eigenfunctions helps to
reduce the size of configuration space and is beneficial in studies
of the systems where selection of states of specific spin symmetry
is crucial. In order to achieve this, we combine the method to calculate
$U(n)$ generator matrix elements developed by Robb and Downward~[\onlinecite{downward_1977}]
with the approach of Gould and Battle to calculate $U(2n)$ generator
matrix elements~[\onlinecite{battle_1993}]. We also compare
and contrast the spin density formulated in terms of the spin-independent
unitary generators arising from the group theory formalism and equivalent
formulation of the spin density representation in terms of the one- and
two-electron charge densities.
to calculate spin densities for CI calculations in a basis of spin
symmetry-adapted functions. Using S$^{2}$ eigenfunctions helps to
reduce the size of configuration space and is beneficial in studies
of the systems where selection of states of specific spin symmetry
is crucial. In order to achieve this, we combine the method to calculate
$U(n)$ generator matrix elements developed by Robb and Downward~[\onlinecite{downward_1977}]
with the approach of Gould and Battle to calculate $U(2n)$ generator
matrix elements~[\onlinecite{battle_1993}]. We also compare
and contrast the spin density formulated in terms of the spin-independent
unitary generators arising from the group theory formalism and equivalent
formulation of the spin density representation in terms of the one- and
two-electron charge densities.
Date Issued
2018-06-15
Date Acceptance
2017-11-17
Citation
International Journal of Quantum Chemistry, 2018, 118 (12)
ISSN
0020-7608
Publisher
Wiley
Journal / Book Title
International Journal of Quantum Chemistry
Volume
118
Issue
12
Copyright Statement
© 2017 The Authors International Journal of Quantum Chemistry Published by Wiley Periodicals, Inc. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
License URL
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Grant Number
EP/I032517/1
Subjects
Science & Technology
Physical Sciences
Chemistry, Physical
Mathematics, Interdisciplinary Applications
Physics, Atomic, Molecular & Chemical
Chemistry
Mathematics
Physics
configuration interaction
configuration state function
quantum chemistry
spin density
unitary group approach
MANY-ELECTRON PROBLEM
PERTURBATION-THEORY CALCULATIONS
GROUP THEORETICAL APPROACH
ADJOINT TENSOR-OPERATORS
MATRIX-ELEMENTS
DEPENDENT OPERATORS
EXPLICIT FORMULAS
GENERAL FORMALISM
MOLECULAR-SYSTEMS
U(2N) GENERATORS
0306 Physical Chemistry (Incl. Structural)
0307 Theoretical And Computational Chemistry
Chemical Physics
Publication Status
Published
Article Number
e25559
Date Publish Online
2017-12-07