I-H Electronic Structure of a Molecule in Solution

The three dimensional reference interaction site model integral equation theory (3D­RISM) combined with the ab initio molecular orbital method (3D­RISM­ SCF) is applied to a solvated macro molecular system. The solvation structure around a solute molecule is obtained from the 3D­RISM integral equation under the electrostatic potential of the solute molecule, calculated by the ab initio molecular orbital theory. The electrostatic potential should be calculated on each grid point in the three dimensional real space. Therefore, the calculation of the electrostatic potential is the most time consuming part in this method. In this paper, we propose a new procedure to save the compu­ tational cost for calculating the electrostatic potential and the solvated fock matrix.