GAS-PHASE SOLVATION OF BENZENE BY 2-8 ARGON ATOMS - A MOLECULAR-DYNAMICS STUDY WITH AB-INITIO INTERMOLECULAR POTENTIAL

Benzene ... Ar-n clusters (n = 2, 3, 5, 7, 8) were studied by constant -energy molecular dynamics simulations using an ab initio intermolecul ar potential for the benzene ... Ar interaction. Stationary points for each cluster were generated by the quenching technique. For clusters with n greater than or equal to 3, the relative populations of energet ically less favorable two-sided and bridgelike structures were found t o be higher than the population of global minima having one-sided stru ctures. For benzene ... Ar-2, the relative population of the global mi nimum (two-sided structure) was found to be lower than the population of the local minimum with the one-sided structure. The preference of b ridged and two-sided structures for clusters with n greater than or eq ual to 3 and one-sided structure for benzene ... Ar-2 is due to the en tropy. A textbook example is the benzene ... Ar-8 cluster where the gl obal minimum having seven argons on one side of the benzene ring and o ne argon on the opposite side is populated 5-8 times less than the les s stable minimum with a bridgelike structure.