CALCULATION OF HYDRATION FREE-ENERGY FOR A SOLUTE WITH MANY ATOMIC SITES USING THE RISM THEORY - A ROBUST AND EFFICIENT ALGORITHM

We have developed an algorithm for solving the reference interaction s ite 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 and is judiciously constructed. Various considerat ions are given so that the computer time can be saved as much as possi ble. The robustness and high efficiency of the algorithm has been demo nstrated for calculating hydration free energies of Met-enkephalin (a peptide with 75 sites) with different conformations. The Jacobian matr ix is treated as part of the input data, and it has been found that th e same matrix can be used for a considerably large set of different co nformations of the solute molecule. (C) 1997 by John Wiley & Sons, Inc .