Masahiro KINOSHITA (Kyoto Univ.), Yuko OKAMOTO and Fumio HIRATA
[J. Comp. Chem. 18, 1320 (1997)]
We have developed a rebust and very efficient algorithm for solving the reference interaction site model (RISM) equations for water near a solute molecule with many atomic sites (interaction sites). It is a hybrid of the Newton-Raphson and Picard methods. Various considerations are given so that the computer time can be saved as greatly as possible. It has been demonstrated for calculating hydration free energies of metenkephalin (a peptide with 73 sites) with different conformations. Its stability is quite insensitive to the initial guess. The Jacobian matrix is treated as part of the input data, and even the same matrix can be used for another conformation unless the conformation is considerably different from the last one.