DefPol: New procedure to build molecular surfaces and its use in continuum solvation methods

We present a method to define van der Waals, solvent-accessible, and solvent-excluding molecular surfaces with their partition in nonoverlapping Ž . surface portions tesserae . The procedure is more efficient than those available in the literature to describe solvent effects on molecular systems of large size, and it can also be applied to solutes of small size without reducing the accuracy of the output and without increasing computational times. All the tesserae are expressed in terms of spherical triangles, having all the characterizing elements Ž . vertices, centers, etc. analytically defined. The method was tested by comparing Ž the results for the surface area and the solvation free energy decomposed in . electrostatic, dispersion, and steric contributions obtained using the GEPOL procedure within the framework of the polarizable continuum model solvation method. These comparisons regard 87 molecules at the molecular mechanics level and 28 molecules at the ab initio Hartree]Fock level: the results are quite satisfactory. Q 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1758]1776, 1998