ELECTRONIC-STRUCTURE OF DONOR SPACER ACCEPTOR MOLECULES OF POTENTIAL INTEREST FOR MOLECULAR ELECTRONICS .1. DONOR-PI SPACER ACCEPTOR

A self-consistent reaction field method is incorporated in a ZDO based semi-empirical quantum mechanical calculation method to account for solvent effects in calculated spectroscopical properties. Absorption spectra for a number of donor-pi spacer-acceptor molecules, which are of interest in connection to molecular electronics, are calculated and compared with experimental results. The solvent dependence of the spectra of 1-julolidyl-4-trifluoromethylphenyl-butadiene (JUL) is calculated and the effects of the different donors are discussed. The amount of direct charge separation upon excitation is estimated to about 10-15% of a complete transfer of one electron. The dipole moments of very polar excited states are canceled out during the configuration interaction (CI) calculation. Thus, the excited states after CI have just moderate dipole moments.