INTERMOLECULAR GROUND AND EXCITED-STATE POTENTIAL-ENERGY SURFACES AND CHARGE-TRANSFER SPECTRUM OF BENZENE - TCNE ELECTRON-DONOR ACCEPTOR COMPLEX

The six-dimensional intermolecular potential energy surface of the benzene:tetracyanoethylene (TCNE) electron donor-acceptor (EDA) complex has been explored, using a combination of ab initio and semiempirical quantum mechanical calculations, at 4732 discrete intermolecular geometries. Spectroscopic INDO calculations were also performed at a subset of the total sampled configurations. The charge-transfer absorption lineshape was then calculated according to a previously described semiclassical approach, using the improved ab initio potential to average the spectrum over the donor-acceptor distance coordinate, R, in place of the previously employed harmonic approximation. The calculated lineshape was found to be in good agreement with the experimental gas phase optical absorption spectrum.