Journal of Physical Chemistry A, Vol.104, No.11, 2362-2366, 2000
Calculation of the ionization potentials and electron affinities of bacteriochlorophyll and bacteriopheophytin via ab initio quantum chemistry
Ionization potentials (IP) and electron affinities (EA) are calculated for bacteriopheophytin (BPh) and bacteriochlorophyll (BChl) in the photosynthetic reaction center utilizing density functional methods implemented in a parallel version of the JAGUAR electronic structure code. These quantities are studied as a function of basis set size and molecular geometry. The results indicate the necessity of using large basis sets with diffuse functions in order to obtain reliable IP and EA in the gas phase. The relative reduction potentials of BChl and BPh in dimethylformamide solution are also calculated and compared with experimental results. Excellent agreement between theory and experiment is obtained when ligand binding of solvent molecules to the central Mg atom of BChl is incorporated in the calculations.
Keywords:PHOTOSYNTHETIC REACTION CENTER;CONTINUUM DIELECTRIC THEORY;RHODOPSEUDOMONAS-VIRIDIS;CHARGE SEPARATION;ENERGIES;GAUSSIAN-2;EXCHANGE