Ab initio potential energy surface and second virial coefficient for Asp-His-Ser trimer

Abstract

HF level of ab initio calculations with basis-set 6-31G including full counterpoise correction has<br />been applied to compute the AspHis potential with the Ser and HisSer potential with the Asp in<br />AspHisSer trimer. The potential energy surface has a minimum of -16.765 kcal/mol in R1=1.912<br />nm and R2=2.719 nm. The optimum computed curves for two interactions were fitted with<br />intermolecular pair potential models, including of Lennard-Jones, Kihara, Buckingham Exp-6 and<br />Buckingham Exp-6-8 potentials. The Buckingham exponential potentials gave the best fit. These<br />potentials have been used to calculate the second virial coefficient for AspHis-Ser and Asp-HisSer<br />interactions. As we expected B2 for Asp-HisSer interaction was more negative from AspHis-Ser<br />interaction.