Quantum Mechanics Moller-Plesset corrections

A recent Monte Carlo study of structure of the dilute aqueous solution of methane from this Laboratory involves one methane molecule and 124 water molecules at 25°C at liquid water density. The configurational energy of the system is developed under the assumption of pairwise additivity using potential functions representative of initio quantum mechanical calculations for both the water-water and methane-water interactions. For the water-water interaction we have carried over the MCY-CI potential function used in our previous study of the structure of liquid water reviewed in the preceeding section. For the methane water interaction energy, we have recently reported an analytical potential function representative of quantum mechanical calculations based on SCF calculations and a 6-31G basis set, with correlation effects Included via second order Moller-Plesset (MP) corrections,52 This function was used for the methane-water con-... 

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