Theoretical Study of Electron Transfer Mechanism in Biological Systems with a QM (MRSCI+DFT)/MM method Toshikazu Takada, RIKEN

The goal of this project is to understand the charge separation mechanisms in biological systems using the molecular orbital theories. Specially, the electron transfer in the photosynthetic reaction center is focused on, since the efficiency in use of the solar energy is extraordinary and the reason for it is still kept unknown. Here, a QM/MM theoretical scheme is employed to take the effects of the surrounding proteins onto the pigments into account. To describe the excited electronic structures, a unified theory by MRSCI and DFT is newly invented. For atoms in the MM space, a new sampling method has been also created, based on the statistical physics. By using these programs, the excited and positively charged states of the special pair, that is, chlorophyll dimmer are planning to be calculated this year.