First principle study of proton transfer in the green fluorescent protein (GFP): Ab initio PES in a cluster model

► CASSCF and MRCI calculations of three-dimensional PES for the proton chain transfer in GFP. ► The results are contrasted with those of other computational studies using both CASPT2 method and DFT method. ► The results are compared with the experimental findings for GFP in the full protein environment.