An efficient implementation of the three-dimensional reference interaction site model (3D-RISM) theory to the fragment molecular orbital (FMO) method was proposed. The method is referred to as FMO/3D-RISM method. The method allows us to treat an electronic structure of whole part of macromolecules, such as protein, as well as a solvent distribution around the solute macromolecules. The electrostatic potential should be calculated on grid point in the three-dimensional real space witch is used in 3D-RISM theory. Therefore, the reducing the computational cost to calculate the electrostatic potential is most serious concern. In this article, we propose a procedure to save the computational cost for calculating the electrostatic potential in the framework of FMO method. The strategy of this procedure is to evaluate the electrostatic potential and the solvated Fock matrix in different ways, depending on the distance between solute and solvent. In the vicinity of solute molecule, the electrostatic potential is evaluated directly by integrating the molecular orbitals of monomer fragments of solute molecule, whereas that is described as the superposition of multipole interactions by using Taylor expansion of the electronic distribution of monomer fragment. The results are compared with those from the other methods. We apply the FMO/3D-RISM method to investigate the selective binding of cellulose by cellulose binding module (CBM).

Efficient implementation of 3D-RISM theory to the FMO method, and its applications

248th National Meeting (2014)

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