Combined Self-Consistent-Field and Spin-Flip Tamm-Dancoff Density Functional Approach to Potential Energy Surfaces for Photochemistry.
We present a new approach to calculating potential energy surfaces for photochemical reactions by combining self-consistent-field calculations for single-reference ground and excited states with symmetry-corrected spin-flip Tamm-Dancoff approximation calculations for multireference electronic states. The method is illustrated by an application with the M05-2X exchange-correlation functional to cis-trans isomerization of the penta-2,4-dieniminium cation, which is a model (with three conjugated double bonds) of the protonated Schiff base of retinal. We find good agreement with multireference configuration interaction-plus-quadruples (MRCISD+Q) wave function calculations along three key paths in the strong-interaction region of the ground and first excited singlet states.
†Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, United States.
Xuefei
X
Xu
‡Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Overman Hall, Bowling Green, Ohio 43403, United States.
Samer
S
Gozem
‡Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Overman Hall, Bowling Green, Ohio 43403, United States.|§Dipartimento di Biotecnologia, Chimica and Farmacia, Università di Siena, via A. Moro 2, I-53100 Siena, Italy.
Massimo
M
Olivucci
†Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, United States.
Donald G
DG
Truhlar
SF2 method; broken symmetry; conical intersection; electronically excited states; multireference configuration interaction; time-dependent density functional theory