ELECTRON-BINDING ENERGY AND LONG-RANGE ELECTRONIC COUPLING - A THEORETICAL-STUDY

Electronic couplings in long-range electron transfer have been calcula ted using ab initio molecular orbital theory to investigate the effect of the binding energy of the electron on the decay of through-space a nd through-bond couplings. Through-space and through-bond couplings fo r anions and cations of the CF3 dimer and of CnH2n and CnF2n chains we re calculated by ab initio molecular orbital theory. The anions and ca tions provide systems for which the electron binding energies, B-e, di ffer by about a factor of 10. Through-space couplings decay exponentia lly, exp(-beta R), with increasing distance, R, between the donor/acce ptor carbon atoms. The decay coefficient beta varies approximately as B-e(1/2). In contrast, the decay coefficients for through-bond couplin g in CnF2n and CnH2n chains are not affected significantly by the bind ing energy of the electron. (C) 1996 American Institute of Physics.