THE C6H6-(H2O)(2) COMPLEX - THEORETICAL PREDICTIONS OF THE STRUCTURE,ENERGETICS, AND TUNNELING DYNAMICS

A detailed theoretical study of the C6H6-(H2O)(2) complex is presented . We characterize the structure and energy by means of various potenti als and correlated ab initio calculations. The potential surface is ex tremely flat but the structures obtained with the empirical potentials and abinitio optimizations agree fairly well. Transition states and c orresponding reaction paths are calculated for four possible degenerat e rearrangements. The splittings for these-mechanisms are calculated f rom quantum simulations with the diffusion Monte Carlo (DMC) approach We predict that two splittings should be observable in the spectrum. T he DMC calculations also allow prediction of vibrationally averaged st ructures, bond energies, and rotational constants. (C) 1997 American I nstitute of Physics.