A MOLECULAR-DYNAMICS STUDY OF METHANOL NEAR THE LIQUID GLASS-TRANSITION

Molecular dynamics simulations of supercooled liquid and glassy methanol are presented, based on an intermolecular potential derived from liquid data. In the supercooled liquid, atom-atom distribution functions for the methyl groups reveal a split first peak that might be observed with diffraction experiments. The nature of the hydrogen-bonded network has been characterized. The fraction of nonbonded molecules is shown to obey an Arrhenius law, with an activation energy similar to that derived from the hydrogen bond lifetimes. The temperature dependence of the self-diffusion coefficient has been analyzed in detail, along with the behavior of the van Hove self-correlation function, the incoherent-structure factor, and orientational correlation functions for intramolecular OH and OC bond vectors. A brief discussion of the collective dynamics is given for the supercooled liquid.