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Calculation of the electron transfer coupling matrix element in diabatic reactions



Electron transfer coupling matrix elements, T values, are evaluated for three typical electron transfer (ET) systems: phenoxyl radical–phenol, DNA fragments, and copper-containing nitrite reductase. Fragment charge difference method is improved by introducing the Pipek-Mezey localization method. We found that T values are stably evaluated by using beta lowest unoccupied molecular orbitals, which are significantly more easily found compared to alpha ET orbitals. This technique is essential for metal-containing ET systems. Redox-active orbitals for the donor and accepter sites are derived by localizing the ET orbitals, and other related parameters such as the state energy gap and the localization index are also obtained. These orbitals and parameters are very useful to characterize their ET reactions. These practical techniques can be utilized for other general ET reactions. © 2012 Wiley Periodicals, Inc.