The primary event that initiates vision is the photoinduced isomerization of retinal in the visual pigment rhodopsin (Rh). Here, we use a scaled quantum mechanics/molecular mechanics potential that reproduces the isomerization path determined with multiconfigurational perturbation theory to follow the excited-state evolution of bovine Rh. The analysis of a 140-fs trajectory provides a description of the electronic and geometrical changes that prepare the system for decay to the ground state. The data uncover a complex change of the retinal backbone that, at 60-fs delay, initiates a space saving ‘‘asynchronous bicycle-pedal or crankshaft’’ motion, leading to a conical intersection on a 110-fs time scale. It is shown that the twisted structure achieved at decay features a momentum that provides a natural route toward the photoRh structure recently resolved by using femtosecond-stimulated Raman spectroscopy.

FRUTOS L., M., Andruniów, T., Santoro, S., Ferré, N., & Olivucci, M. (2007). Tracking the Excited State Time Evolution of the Visual Pigment with Multiconfigurational Quantum Chemistry. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 104(19), 7764-7769 [10.1073/pnas.0701732104].

Tracking the Excited State Time Evolution of the Visual Pigment with Multiconfigurational Quantum Chemistry

OLIVUCCI, MASSIMO
2007

Abstract

The primary event that initiates vision is the photoinduced isomerization of retinal in the visual pigment rhodopsin (Rh). Here, we use a scaled quantum mechanics/molecular mechanics potential that reproduces the isomerization path determined with multiconfigurational perturbation theory to follow the excited-state evolution of bovine Rh. The analysis of a 140-fs trajectory provides a description of the electronic and geometrical changes that prepare the system for decay to the ground state. The data uncover a complex change of the retinal backbone that, at 60-fs delay, initiates a space saving ‘‘asynchronous bicycle-pedal or crankshaft’’ motion, leading to a conical intersection on a 110-fs time scale. It is shown that the twisted structure achieved at decay features a momentum that provides a natural route toward the photoRh structure recently resolved by using femtosecond-stimulated Raman spectroscopy.
FRUTOS L., M., Andruniów, T., Santoro, S., Ferré, N., & Olivucci, M. (2007). Tracking the Excited State Time Evolution of the Visual Pigment with Multiconfigurational Quantum Chemistry. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 104(19), 7764-7769 [10.1073/pnas.0701732104].
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11365/8041
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