A rapid approximation to the solvent accessible surface areas of atoms

An analytical expression for approximate atomic and molecular van der Waals and solvent accessible surface areas is described. The treatment is based on the probabilistic method of Wodak and Janin1 but with modifications which allow it to be applied to the calculation of atomic surface areas. The calculation is a pairwise function of atomic positions and radii and is therefore quite rapid. We compare the results of this method with exact areas, list the first and second derivatives of the function and provide a FORTRAN subroutine on disk which calculates the approximate atomic areas from atomic coordinates and connectivity. We also provide some standard test molecules on disk.