文摘
We present an ab initio study of the optical absorption properties of a particularly interesting fluorescentprotein (E2GFP), whose complex photophysics still escapes elucidation. In particular, we focus on the role ofthe protein environment, showing that the effects of both nearby residues and the external field due to residuesnot accounted for explicitly are needed to properly reproduce the experimental data. The spectra calculatedtaking such contributions into account provide for the first time a robust identification of the states relevantfor the photophysics of this system.