(52b) Solvent Effect On the Ultrafast Spectra In Water Solution: Explicit and Implicit Solvation

In the framework of continuous medium theory, a new form of the electrostatic free energy of nonequilibrium solvation has been derived by the method of constrained equilibrium state^[1]. This form has been further deduced to solve the electron transfer^[2] and hydrated electron^[3] problems, and in this work to treat the solvent effect on the ultrafast UV/Vis absorption spectra in water solution with respect to both explicit and implicit solvation strategies^[4]. For the explicit solvation, the newly inferred energy expression was implemented by means of modifying the nonequilibrium module of the averaged solvent electrostatic potential/molecular dynamics (M-ASEP/MD) program, which permits an atomic-level description of the solvent and the mutual polarization between the solute and solvent molecules. For the implicit solvation, an approximation of point dipole and sphere cavity was employed with considering the solvent as a uniform and continuous polarizable dielectric medium. In addition, a new method of determination of the cavity radius was proposed, taking the short-range dispersion/repulsion and long-range electrostatic interactions between the solute and solvent molecules into account with the aid of the MD simulations. Sequentially, the two solvation strategies that are based on our nonequilibrium solvation theory were performed to study the solvatochromic shift of formaldehyde, a representative chromophore molecule, in water solvent and verified to show self-consistence with each other.

References

1 X. Y. Li, F. C. He, K. X. Fu, W. J. Liu, J. Theor. Comput. Chem. 2010, 9, Supp. 1, 23–37.

2 X. Y. Li, Q. D. Wang, J. B. Wang, J. Y. Ma, K. X. Fu, F. C. He, Phys. Chem. Chem. Phys. 2010, 12, 1341–1350.

3 X. J. Wang, Q. Zhu, Y. K. Li, X. M. Cheng, X. Y. Li, K. X. Fu, F. C. He, J. Phys. Chem. B 2010, 114, 2189–2197.

4 Y. K. Li, Q. Zhu, X. Y. Li, K. X. Fu, X. J. Wang, X. M. Cheng, J. Phys. Chem. A 2011, 115, 232.