EXAMINATION OF SOME NEW CONFIGURATIONS OF METHANOL-WATER HETERO DIMERSYSTEM BY MOLECULAR-ORBITAL AND DENSITY-FUNCTIONAL CALCULATIONS

Ab initio calculations have been performed for the methanol-water hete ro dimer system using the 3-21G basis set. Four new complex structures have been examined in addition to the old one. Among the four, two co mplex structures could exist. These two structures are optimized by th e 3-21G (C and O) basis set (with inclusion of polarization functions except for hydrogen). The main parameters for a hydrogen bonded struc tures, i.e., hydrogen bond length and the interaction energy, have bee n calculated. Basis set superposition errors have been eliminated by u sing the full counterpoise correction method. The chemical hardness an d the electronic chemical potential have been calculated for both mono mers and for the complex structures. The stability of the various meth anol-water complex configurations are discussed in relation to the sta bility of the monomers using the values of dipole moment, atomic charg e and hardness.