Electronic structural properties and photosynthesis

A review of recent theoretical studies of molecules of interest to photosynthesis is given, in which the results of ab initio self‐consistent‐field plus configuration‐interaction studies are discussed. Ground‐state and low‐lying excited singlet and triplet state descriptions are presented for six molecules, including Mg‐porphine, Mg‐chlorin, ethyl chlorophyllide a , and their corresponding magnesium‐free analogs. The data are then used to rationalize a variety of observed properties, including molecular orbital structure, ionization potentials, chemical reactivity, Franck‐Condon transition energies, oscillator strengths, transition polarizations, and other properties. As a result, relatively comprehensive and complete descriptions of the electronic structural features of chlorophyll a and related molecules are obtained, which are in general in good agreement with available experimental data, but which also provide new concepts and reinterpretation of existing data in several instances.