A CASPT2//CASSCF Study of Vertical and Adiabatic Electron Transitions of Acrolein in Water Solution
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- 作者：Aurora Muñ ; oz Losa ; Ignacio Fdez. Galvá ; n ; Manuel A. Aguilar ; M. Elena Martí ; n
- 刊名：Journal of Physical Chemistry B
- 出版年：2007
- 出版时间：August 23, 2007
- 年：2007
- 卷：111
- 期：33
- 页码：9864 - 9870
- 全文大小：72K
- 年卷期：v.111,no.33(August 23, 2007)
- ISSN：1520-5207
文摘
The 1(n 
pi.gif" BORDER=0 >*) excited-state of acrolein in liquid water was studied theoretically by using the averaged solventelectrostatic potential from molecular dynamics method (ASEP/MD). The model combines a multireferenceperturbational CASPT2//CASSCF treatment in the description of the solute molecule with NVT moleculardynamics simulations in the description of the solvent. In this paper, we present two alternative methods forcalculating solvent shift on adiabatic transitions and their performance is analyzed. In the first method, thefree energy change during an adiabatic transition is calculated classically by using the free energy perturbationmethod. In the second method, it is calculated from the quantum values of the vertical absorption and emissionelectron transition energies. The 1(n pi.gif" BORDER=0 >*) excitation is accompanied by a charge flux from the oxygen tothe carbon skeleton, this charge flux decreases the dipole moment of the excited-state with respect to theground state value and, consequently, the solute-solvent interaction energy. This effect destabilizes the excited-state with respect to the ground state and produces a blue shift in the absorption and emission bands. For theemission process, there also exists an additional destabilization due to a partial desolvation of the excitedstate. The effect of the solvent electron polarization, the inclusion of the solute electron correlation, and theuse of relaxed geometries in solution on the calculated solvent shift of the absorption and emission spectraare also analyzed.
pi.gif" BORDER=0 >*) excited-state of acrolein in liquid water was studied theoretically by using the averaged solventelectrostatic potential from molecular dynamics method (ASEP/MD). The model combines a multireferenceperturbational CASPT2//CASSCF treatment in the description of the solute molecule with NVT moleculardynamics simulations in the description of the solvent. In this paper, we present two alternative methods forcalculating solvent shift on adiabatic transitions and their performance is analyzed. In the first method, thefree energy change during an adiabatic transition is calculated classically by using the free energy perturbationmethod. In the second method, it is calculated from the quantum values of the vertical absorption and emissionelectron transition energies. The 1(n pi.gif" BORDER=0 >*) excitation is accompanied by a charge flux from the oxygen tothe carbon skeleton, this charge flux decreases the dipole moment of the excited-state with respect to theground state value and, consequently, the solute-solvent interaction energy. This effect destabilizes the excited-state with respect to the ground state and produces a blue shift in the absorption and emission bands. For theemission process, there also exists an additional destabilization due to a partial desolvation of the excitedstate. The effect of the solvent electron polarization, the inclusion of the solute electron correlation, and theuse of relaxed geometries in solution on the calculated solvent shift of the absorption and emission spectraare also analyzed.