Analytic gradients and derivative couplings for configuration interaction with all single excitations and one double excitation—En route to nonadiabatic dynamics
Abstract
We present analytic gradients and derivative couplings for the simplest possible multireference configuration interaction method, CIS-1D, an electronic structure Ansatz that includes all single excitations and one lone double excitation on top of a Hartree–Fock reference state. We show that the resulting equations are numerically stable and require the evaluation of a similar number of integrals as compared to standard CIS theory; one can easily differentiate the required frontier orbitals (h and l) with minimal cost. The resulting algorithm has been implemented within the Q-Chem electronic structure package and should be immediately useful for understanding photochemistry with S0–S1 crossings.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 11, 2020
- Source ID
- 10.1063/5.0018441
Entities
People
- Hung-Hsuan Teh
- Joseph E Subotnik
Organizations
- Air Force Office of Scientific Research
- University of Pennsylvania