Variational Active Space Selection with Multiconfiguration Pair-Density Functional Theory

Daniel S. King

doi:10.1021/acs.jctc.3c00792

2023-10-31

PRE

Daniel S. King

Donald G. Truhlar *

Laura Gagliardi *

DOI：10.1021/acs.jctc.3c00792

原文链接

原文求助

摘要

En 中文

The selection of an adequate set of active orbitals for modeling strongly correlated electronic states is difficult to automate because it is highly dependent on the states and molecule of interest. Although many approaches have shown some success, no single approach has worked well in all cases. In light of this, we present the discrete variational selection (DVS) approach to active space selection, in which one generates multiple trial wave functions from a diverse set of systematically constructed active spaces and then selects between these wave functions variationally. We apply this DVS approach to 207 vertical excitations of small-to-medium-sized organic and inorganic molecules (with 3 to 18 atoms) in the QUESTDB database by (i) constructing various sets of active space orbitals through diagonalization of parametrized operators and (ii) choosing the result with the lowest average energy among the states of interest. This approach proves ineffective when variationally selecting between wave functions using the density matrix renormalization group (DMRG) or complete active space self-consistent field (CASSCF) energy but is able to provide good results when variationally selecting between wave functions using the energy of the translated PBE (tPBE) functional from multiconfiguration pair-density functional theory (MC-PDFT). Applying this DVS-tPBE approach to selection among state-averaged DMRG wave functions, we obtain a mean unsigned error of only 0.17 eV using hybrid MC-PDFT. This result matches that of our previous benchmark without the need to filter out poor active spaces and with no further orbital optimization following active space selection of the SA-DMRG wave functions. Furthermore, we find that DVS-tPBE is able to robustly and effectively select between the new SA-DMRG wave functions and our previous SA-CASSCF results.

Keyword:

MATRIX RENORMALIZATION-GROUP

CORRELATED-PARTICIPATING-ORBITALS

2ND-ORDER PERTURBATION-THEORY

AB-INITIO CALCULATIONS

BASIS-SETS

NATURAL ORBITALS

EXCITED-STATES

CONSTRUCTION

OPTIMIZATION

CASPT2