Quantum adiabatic umbrella sampling: The excited state free energy surface of an electron-atom pair in solution

A quantum umbrella sampling method to generate free energy surfaces for excited-state as well as ground state reactions in solution is presented. The approach is applied to the photodetachment of an electron from aqueous chloride in the lowest excited state channel (corresponding to the lowest charge-transfer-to-solvent state). An activation free energy barrier due to solvent reorganization is identified and discussed. (C) 1996 American Institute of Physics.