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Title: Optimizing minimum free-energy crossing points in solution: Linear-response free energy/spin-flip density functional theory approach

Examining photochemical processes in solution requires understanding the solvent effects on the potential energy profiles near conical intersections (CIs). For that purpose, the CI point in solution is determined as the crossing between nonequilibrium free energy surfaces. In this work, the nonequilibrium free energy is described using the combined method of linear-response free energy and collinear spin-flip time-dependent density functional theory. The proposed approach reveals the solvent effects on the CI geometries of stilbene in an acetonitrile solution and those of thymine in water. Polar acetonitrile decreases the energy difference between the twisted minimum and twisted-pyramidalized CI of stilbene. For thymine in water, the hydrogen bond formation stabilizes significantly the CI puckered at the carbonyl carbon atom. The result is consistent with the recent simulation showing that the reaction path via this geometry is open in water. Therefore, the present method is a promising way of identifying the free-energy crossing points that play an essential role in photochemistry of solvated molecules.
Authors:
 [1]
  1. Fukui Institute for Fundamental Chemistry, Kyoto University, Sakyo-ku, Kyoto 606-8103 (Japan)
Publication Date:
OSTI Identifier:
22310735
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 141; Journal Issue: 16; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ACETONITRILE; ATOMS; CARBON; CARBONYLS; DENSITY FUNCTIONAL METHOD; FREE ENERGY; HYDROGEN; MOLECULES; POTENTIAL ENERGY; SIMULATION; SOLUTIONS; SOLVENTS; SPIN FLIP; STILBENE; THYMINE; TIME DEPENDENCE; WATER