Computer simulation of the effect exerted by argon matrix on the internal rotation barriers and torsional states of methanol molecule

Abstract

In the approximation B3LYP/cc-pVTZ, the geometry of a methanol molecule surrounded by eight argon atoms has been optimized. Using a fixed configuration of argon atoms, the internal rotation barriers of methyl and hydroxyl groups, the values of which are compared with that for a free molecule, have been computed. It has been found that insignificant differences in the form of the potential function as compared to a free molecule occur only on rotation of a hydroxyl group, being independent of the methyl group position with respect to the argon lattice. The torsional state energies of a methanol molecule surrounded by argon atoms have been computed taking the difference in the potential functions of the hydroxyl group rotation with respect to the lattice and internal rotation in a free molecule as a perturbing factor. According to the results of these computations, degeneracy of the Е-type states is relieved with a slight increase in splitting of the ground torsional state.