MONTE CARLO STUDY OF THE SELF-ASSOCIATION OF METHANOL IN BENZENE

Monte Carlo (MC) calculations have been carried out for four benzene-methanol solutions within conventional NVT ensemble by the Metropolis scheme. New potential functions have been prepared for benzene-benzene and benzene-methanol interactions. They are based on extensive LCAO SCF molecular orbital calculations with the Moller-Presset perturbation method and STO-3G basis set. For methanol-methanol interactions, the potential function proposed by Jorgensen is adopted. The mole fractions of methanol in the four benzene-methanol solutions studied are 0.05, 0.10, 0.25 and 0.5, respectively. The MC results clearly show the self-association of methanol, the degree of which increases with increasing the methanol content. It is also found that the shape of self-associating complex of methanol molecules changes from spherical in lower methanol content to flexible chain-like in concentrated solutions. The fraction of methanol molecules which exist as monomer is estimated for each solution and proved to be consistent generally with spectroscopic informations.