Good Vibrations: Calculating Excited-State Frequencies Using Ground-State Self-Consistent Field Models

J Chem Theory Comput. 2022 Dec 13;18(12):7286-7297. doi: 10.1021/acs.jctc.2c00672. Epub 2022 Nov 29.

Abstract

The use of Δ-self-consistent field (SCF) approaches for studying excited electronic states has received a renewed interest in recent years. In this work, the use of this scheme for calculating excited-state vibrational frequencies is examined. Results from Δ-SCF calculations for a set of representative molecules are compared with those obtained using configuration interaction with single substitutions (CIS) and time-dependent density functional theory (TD-DFT) methods. The use of an approximate spin purification model is also considered for cases where the excited-state SCF solution is spin-contaminated. The results of this work demonstrate that an SCF-based description of an excited-state potential energy surface can be an accurate and cost-effective alternative to CIS and TD-DFT methods.

MeSH terms

  • Quantum Theory*
  • Vibration*