Many-body potentials and dynamics based on diatomics-in-molecules: Vibrational frequency shifts in ArnHF (n=1-12,62) clusters

The conjecture that limited basis diatomics-in-molecules type potentials may serve as an accurate representation of many-body interactions is explored through molecular dynamics simulations of ArnHF (n=1-12,62). The important ingredient in the constructed potentials is the inclusion of ionic configurations of HE Once the admixture between ionic and covalent configurations is calibrated by reference to an ab initio surface of the ArHF dimer, a single three-body potential energy surface is defined, and used in subsequent simulations of larger clusters. The vibrational frequencies of HE which are computed from velocity-velocity autocorrelation functions, quantitatively reproduce the cluster size dependent redshifts. (C) 1996 American Institute of Physics.