Electronic excitation energy calculation by the fragment molecular orbital method with three-body effects

Abstract

A scheme for full quantum electronic excited state calculation is proposed that is based on the fragment molecular orbital (FMO) method with three-body effects. The accuracy and efficiency of this scheme is checked by calculating the excitation energy of hydrated formaldehyde and hydrated phenol. In all cases, three-body effects improved the excitation energy by the one- and two-body FMO methods with small computational cost, and the excitation energy approached more closely the full calculation value. The results also show that the three-body effects were relatively large and cannot be neglected.

Fragment molecular orbital calculations for excitation energies of blue- and yellow-fluorescent proteins

“…We [22,33,34] have had a stance that CIS(D) type calculations provide a set of cross-reference data for TDDFT calculations whose technological developments have still been in progress such as a long range-corrected treatment used in Refs. [23,25,28]. The pigment structures of BFP and YFP are so different from each other [40] (see Figure 1 later) and also differ from those of two RFPs (DsRed [32] and mFruits [35]) that we studied previously [33,34].…”

“…[28], though the basic formulations were common. Our implementation provided an applicability to photoactive proteins, and pilot calculations were carried out for such as DsRed (unpublished).…”

“…As in the case of ground state [2,3], the contribution from electron delocalizations can be taken into account by the FMO2 correction. The set of FMO3 equations of excited state energy [28] has a lengthy form relative to that of FMO2, and we thus refrain to list it here. During pilot calculations, we encountered a problem of spurious excited states associated with the bond-detachment sp 3 -carbon atom [15] by which the fragmentation of chemical bonds is performable without any artificial capping [2,4].…”

“…They demonstrated that the FMO3 treatment is effective in reducing errors of total energy relative to the case of FMO2, especially for the hydrogen-bond systems. Very recently, a paper on the FMO3 treatment for excited states was reported [28], in which a couple of hydrated small molecules were employed as test examples.…”

“…The FMO2/pairwise scheme for excited states [11,25] is used to select contributive amino acid residues which are cast into the excited state layer of MFMO as well as the pigment. We also examine the influence of the threebody correction (FMO3) [26][27][28]. The remaining parts of this Letter are organized as follows.…”