FMO3-LCMO study of electron transfer coupling matrix element and pathway: Application to hole transfer between two triptophanes through cis- and trans-polyproline-linker systems

The linear-combination of fragment molecular orbitals with three-body correction (FMO3-LCMO) is examined for electron transfer (ET) coupling matrix elements and ET pathway analysis, with application to hole transfer between two triptophanes bridged by cis- and trans-polyproline linker conformations. A projection to the minimal-valence-plus-core FMO space was found to give sufficient accuracy with significant reduction of computational cost while avoiding the problem of linear dependence of FMOs stemming from involvement of bond detached atoms.