TD-DFT calculations of the potential energy curves for the trans-cis photo-isomerization of protonated Schiff base of retinal.
One-dimensional potential energy curves for the isomerization of protonated Schiff base of retinal (PSBR) in bacteriorhodopsin (bR), i.e., isomerization from all-trans- to 13-cis-forms, have been calculated by means of time-dependent density functional theory (TD-DFT) calculations, in order to elucidate the mechanism of initial step in photo-absorption. The transition state of the isomerization in the first excited state is located at theta(13-14)=58 degrees , where theta(13-14) means twist angle around the C(13)=C(14) double bond of PSBR The potential barrier is formed by the avoided crossing between S(1) (B(u)-like) and S(2) (A(g)-like) states. The mechanism of the isomerization was discussed on the basis of theoretical results.
Tachikawa
Hiroto
H
Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University, Kita-ku, Sapporo 060-8628, Japan. hiroto@eng.hokudai.ac.jp
Iyama
Tetsuji
T
D004735:Energy Transfer; D007536:Isomerism; D008958:Models, Molecular; D015394:Molecular Structure; D010777:Photochemistry; D011522:Protons; D011789:Quantum Theory; D012172:Retinaldehyde / Q000737:chemistry*; D012545:Schiff Bases / Q000737:chemistry*; D013816:Thermodynamics; D013997:Time Factors
D011522:Protons; D012545:Schiff Bases; D012172:Retinaldehyde