Toward more accurate adiabatic connection approach for multireference wavefunctions

0568898 - ÚFCH JH 2024 RIV US eng J - Článek v odborném periodiku
Matoušek, Mikuláš - Hapka, M. - Veis, Libor - Pernal, K.
Toward more accurate adiabatic connection approach for multireference wavefunctions.
Journal of Chemical Physics. Roč. 158, č. 5 (2023), č. článku 054105. ISSN 0021-9606. E-ISSN 1089-7690
Grant CEP: GA ČR GF23-04302L
Institucionální podpora: RVO:61388955
Klíčová slova: Approximation algorithms * Quantum theory * Statistical mechanics
Obor OECD: Physical chemistry
Impakt faktor: 4.4, rok: 2022
Způsob publikování: Open access

A multiconfigurational adiabatic connection (AC) formalism is an attractive approach to compute the dynamic correlation within the complete active space self-consistent field and density matrix renormalization group (DMRG) models. Practical realizations of AC have been based on two approximations: (i) fixing one- and two-electron reduced density matrices (1- and 2-RDMs) at the zero-coupling constant limit and (ii) extended random phase approximation (ERPA). This work investigates the effect of removing the ´´fixed-RDM´´approximation in AC. The analysis is carried out for two electronic Hamiltonian partitionings: the group product function- and the Dyall Hamiltonians. Exact reference AC integrands are generated from the DMRG full configuration interaction solver. Two AC models are investigated, employing either exact 1- and 2-RDMs or their second-order expansions in the coupling constant in the ERPA equations. Calculations for model molecules indicate that lifting the fixed-RDM approximation is a viable way toward improving the accuracy of existing AC approximations.
Trvalý link: https://hdl.handle.net/11104/0340176