Article
A multireference perturbation method using non-orthogonal Hartree-Fock determinants for ground and excited states
Journal of Chemical Physics
(2013)
Abstract
In this article we propose the ΔSCF(2) framework, a multireference strategy based on second-order perturbation theory, for ground and excited electronic states. Unlike the complete active space family of methods, ΔSCF(2) employs a set of self-consistent Hartree-Fock determinants, also known as ΔSCF states. Each ΔSCF electronic state is modified by a first-order correction from Møller-Plesset perturbation theory and used to construct a Hamiltonian in a configuration interactions like framework. We present formulas for the resulting matrix elements between nonorthogonal states that scale as N2/occN3/virt. Unlike most active space methods, ΔSCF(2) treats the ground and excited state determinants even-handedly. We apply ΔSCF(2) to the H2, hydrogen fluoride, and H4 systems and show that the method provides accurate descriptions of ground- and excited-state potential energy surfaces with no single active space containing more than 10 ΔSCF states.
Keywords
- Perturbation theory,
- Computational chemistry
Disciplines
Publication Date
November 7, 2013
DOI
10.1063/1.4827456
Publisher Statement
© 2013 AIP Publishing LLC.
Citation Information
Shane Yost, Tim Kowalczyk, Troy Van Voorhis (2013) A multireference perturbation method using non-orthogonal Hartree-Fock determinants for ground and excited states. J. Chem. Phys. 139 (17), 174104