A Preliminary Study of Correction for Inter Fragment Interaction Energy (IFIE) between Fragments Sharing Bond Detached Atom (BDA)

Abstract

Recently, the fragment molecular orbital (FMO) method has attracted considerable attention as an electronic structure calculation scheme applicable to macromolecular systems. As a major advantage, a list of inter fragment interaction energies (IFIEs) are straightforwardly obtained from the FMO calculations. It has been well recognized that the IFIE-based analyses are useful to grasp the nature of interactions in the given target system in practical applications. However, there exists a severe limitation that the value of IFIE between covalently bonded fragments takes an abnormally large value (about -15 hartree), and this should degrade the usability of FMO calculations in several cases. In this paper, we examined a correction method to solve this problem, based on the fictitious dissociation processes.