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Updated: Aug 13, 2026

Interactive Molecular Model Assembly with 3D Printing
Published on: August 13, 2020
Locating the lowest free-energy point on conical intersection in polar solvent: reference interaction site model
Shohei Yamazaki1, Shigeki Kato
1Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa, Japan.
Abstract:
We present a theoretical method for locating the lowest free-energy points on conical intersections (CIs) in solution using the reference interaction site model self-consistent field (RISM-SCF) theory. Based on the linear-response theory, the nonequilibrium free energy is defined as a quadratic function of solvation coordinates, the parameters in which are directly obtained by ab initio RISM-SCF calculations. This free energy is easily incorporated into an efficient CI optimization procedure in gas phase. The present method is applied to the cis-trans photoisomerizations of ethylene and methaniminium cation (CH2NH2(+)) in polar solvents. We show that the geometries and energies of CIs are largely affected by the solute-solvent electrostatic interaction. In particular, the hydrogen migration of ethylene observed at CIs in the gas phase disappears in protic solvents due to the large stabilization of the zwitterionic state.
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