Ab initio study of the second virial coefficient protein — protein on the basis of intermolecular potential energy surface

Abstract

Intermolecular potential energy surface (IPS) for protein — protein has been examined using RHF, DFT-B3LYP<br />and MP2 levels of theory with 6-31G, 6-31G* basis sets. A number of basis sets were used in order to evaluate<br />the basis set effects, at all three levels of theory, basis sets has significant effects on the calculated potential<br />energy curves (including position, depth and width of the potential well). Counterpoise (CP) correction has been<br />used to show the extent of the basis set superposition error (BSSE) on the potential energy curves obtained for<br />protein — protein system. The deepest BSSE-corrected potential well have been obtained at B3LYP level of<br />theory with 6-31G basis set. The second virial coefficients calculated this way are fitted to the initial coefficients<br />B2 varying E and ro, eventually some other parameters.