Photoisomerization of phytochrome chromophore models: an XMS-CASPT2 study

Abstract

Phytochromes are a superfamily of photoreceptors that harbor linear tetrapyrroles as chromophores. Upon light illumination, the linear tetrapyrrole chromophore undergoes a double bond isomerization which starts a photocycle. In this...

Green/red light-sensing mechanism in the chromatic acclimation photosensor

“…We also calculated the spectra for the Pr state of RcaE based on the previous quantum mechanics/molecular mechanics (QM/MM) model ( 40 ). Although the calculated spectra were blue-shifted from the experimental absorption maximum as reported in other studies ( 14 , 41 ), our calculated spectra successfully reproduced a large absorption shift between Pg and Pr peaks (67 nm, 0.30 eV) ( Fig. 3B and text S2).…”

Effect of the protein environment on the excited state phenomena in a bacteriophytochrome

“…From a truncated model consisting of only two pyrrole rings, the effects of clockwise and anticlockwise rotations and substitution have been studied. 38 Here, it has been observed that one bond flip becomes a preferred mechanism over hula twist upon carbonyl substitution. Minimal effects of alkyl group substitution were also observed.…”

Minimum-Energy Conical Intersections by Compressed Multistate Pair-Density Functional Theory

“…The CMS-PDFT method gives the correct topology of closely spaced PESs at and near conical intersections. CMS-PDFT may be compared to extended multistate complete active space second-order perturbation theory (XMS-CASPT2), , which has been demonstrated to be a highly accurate quantum chemical method that can describe important dynamic correlation effects at and near the conical intersections that control quenching and other electronically nonadiabatic processes. − Although CMS-PDFT gives results of comparable quality, including near conical intersections, it is advantageous as it is much less expensive.…”