title: Dynamical Correlation Effects on Photoisomerization: Ab Initio Multiple Spawning Dynamics with MS-CASPT2 for a Model trans-Protonated Schiff Base.
abstract: We investigate the photoisomerization of a model retinal protonated Schiff base (trans-PSB3) using ab initio multiple spawning (AIMS) based on multistate second order perturbation theory (MSPT2). Discrepancies between the photodynamical mechanism computed with three-root state-averaged complete active space self-consistent field (SA-3-CASSCF, which does not include dynamic electron correlation effects) and MSPT2 show that dynamic correlation is critical in this photoisomerization reaction. Furthermore, we show that the photodynamics of trans-PSB3 is not well-described by predictions based on minimum energy conical intersections (MECIs) or minimum energy conical intersection (CI) seam paths. Instead, most of the CIs involved in the photoisomerization are far from MECIs and minimum energy CI seam paths. Thus, both dynamical nuclear effects and dynamic electron correlation are critical to understanding the photochemical mechanism.
authors.affiliation: Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University , Beijing 100875, China.|Department of Chemistry and PULSE Institute, Stanford University , Stanford, California 94305, United States.|SLAC National Accelerator Laboratory , Menlo Park, California 94309, United States.
authors.forename: Lihong
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Chemistry and PULSE Institute, Stanford University , Stanford, California 94305, United States.|SLAC National Accelerator Laboratory , Menlo Park, California 94309, United States.|Beijing National Laboratory for Molecular Sciences, Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Chemistry and PULSE Institute, Stanford University , Stanford, California 94305, United States.|SLAC National Accelerator Laboratory , Menlo Park, California 94309, United States.
authors.forename: Todd J
authors.initials: TJ
authors.lastname: Martinez