Automatic Selection of an Active Space for Calculating Electronic Excitation Spectra by MS-CASPT2 or MC-PDFT

Jie J. Bao, Sijia S. Dong, Laura Gagliardi, Donald G. Truhlar

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Multireference methods such as multistate complete active space second-order perturbation theory (MS-CASPT2) and multiconfiguration pair-density functional theory (MC-PDFT) can be very accurate, but they have the disadvantage that they are not black-box methods, and finding a good active space for the reference wave function often requires nonsystematic procedures based on intimate knowledge of the system under study. In this paper, we propose a scheme called the ABC scheme, which is a three-step calculation using three parameters, for automatic selection (without looking at the orbitals and without using any knowledge of the specific system at hand) of the active space (including both the size of the active space and the orbitals in the active space) for MS-CASPT2 or MC-PDFT calculations, and we report tests of the scheme on the first five excitation energies for a set of ten doublet radicals. The results show that the ABC scheme is very successful for both MS-CASPT2 and MC-PDFT for all ten systems considered here.

Original languageEnglish (US)
Pages (from-to)2017-2025
Number of pages9
JournalJournal of Chemical Theory and Computation
Volume14
Issue number4
DOIs
StatePublished - Apr 10 2018

Fingerprint Dive into the research topics of 'Automatic Selection of an Active Space for Calculating Electronic Excitation Spectra by MS-CASPT2 or MC-PDFT'. Together they form a unique fingerprint.

Cite this