OPTICAL-PROPERTIES OF SOLVATED MOLECULES CALCULATED BY A QMMM METHOD - CHLOROPHYLL-A AND BACTERIOCHLOROPHYLL A

We have applied a hybrid quantum mechanical-molecular mechanical (QMMM ) approach to the calculation of electronic-vibrational coupling. To t est the validity of this approach, rye compare results to the steady s tate absorption and emission spectra of chlorophyll a (Chl-a) and bact eriochlorophyll a (BChl-a). We find that the Stokes shift and the widt hs of the spectra are reasonably well represented while the amplitudes of the vibrational side band in both molecules are greatly underestim ated.