MOLECULAR-DYNAMICS SIMULATION OF AN EXCESS CHARGE IN WATER USING MOBILE GAUSSIAN-ORBITALS

For mixed quantum-classical molecular dynamics simulations of solvated excess charges a novel and efficient method to expand the solute electronic wave function in a distributed Gaussian basis with a shell structure is presented. The aggregate of Gaussian orbitals is capable of mimicking the shape fluctuation of the excess charge distribution and its diffusion through the solvent. This approach also offers an easy pathway to treat the solvent electronic polarization in an explicit and self-consistent fashion. As applications, the results of adiabatic molecular dynamics simulations for the hydrated electron and the aqueous chloride are reported. For e(-)/H2O the computed ground state absorption spectrum is discussed. Adiabatic relaxation as well as nonadiabatic transition rates are evaluated-the latter by means of an original Golden Rule formula-and compared to experimental results. In the case of Cl-/H2O the charge transfer to solvent spectra are analyzed. The ability of the mobile basis set method to describe the photodetachment dynamics of an electron from aqueous chloride is also demonstrated. (C) 1995 American Institute of Physics.