Intermolecular potential function for methanol dimer interactions from ab initio calculations

Abstract

Ab initio calculations at the Hartree-Fock SCF (HF-SCF) level have been carried out to determine the interaction energy hypersurface for the methanol dimer. The performance of compact effective core potential basis sets (CEP) in sampling the interaction energy surface of H-bonded systems has been evaluated and compared to all-electron basis sets results. HF-SCF and Møller-Plesset MP2 calculations including electron correlation were compared for selected MeOH dimer geometries. An analytical pair potential expression was determined to fit the 332 calculated CEP-31G**/HF energies and was compared to potentials from the literature. The global minimum on the (MeOH) 2 surface is −4.52 kcal/mol and corresponds to an H-bonded configuration of the two monomers of the form MeOH::OHMe. Weak H bonding at the methyl group corresponding to H bonds of the form MeHO::HCH 2OH and bifurcated H bonds of the form MeHO::H 2CHOH are also observed.