Effect of solvent fluctuations on proton transfer dynamics: a hybrid AM1/MM molecular dynamics simulation on the [H3N-H-NH3](+) system

Combined AM1/TIP3P Molecular Dynamics simulations have been carried out to investigate proton transfer dynamics in aqueous solution for the proton-bou nd ammonia dimer model system. The distance between nitrogen atoms has been fixed to 2.62 Angstrom so that proton transfer events occur every 10-20 ps in average. The chemical reaction is clearly shown to be preceded by a sol vent fluctuation which starts about 700 fs before reaching the transition s tructure. (C) 1999 Elsevier Science B.V. All rights reserved.