Time-Dependent Complete Active Space Embedded in a Polarizable Force Field

• DOI: 10.1021/acs.jctc.8b01152
• Publication Date: 2019-01-29T03:01:48Z
• Authors: Hongbin Liu; Andrew J. Jenkins; Andrew Wildman; Michael J. Frisch; Filippo Lipparini; Benedetta Mennucci; Xiaosong Li
• Keywords: 0103 physical sciences; 01 natural sciences

Electron correlation and environmental effects play important roles in electron dynamics and spectroscopic observables of chemical systems in condensed phase. In this paper, we present a time-dependent complete active space configuration interaction (TD-CASCI) approach embedded in a polarizable force field, MMPol. The present implementation of TD-CASCI/MMPol utilizes a direct matrix-vector contraction, allowing studies of large systems. This scheme is used to study the solvatochromic shift of coumarin 153 in methanol. The TD-CASCI/MMPol approach captures the double excitation character in the excited state wave function and accurately predicts the solvatochromic red-shift of coumarin 153 dye within the experimental range, outperforming linear response time-dependent density functional theory. The effect of using different reference orbitals for the TD-CASCI/MMPol simulation is also investigated, highlighting the need for an unbiased treatment of all electronic states in the energy range of interest.