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Coherent Control of the Primary Event in Human Vision
Samuel Flores and Victor S. Batista
Yale University, Department of Chemistry
(Submitted to J. Phys. Chem. B)
Primary Event in Vision
Ultrafast Photo-Isomerization Mechanism
Technological applications: associative memory devices R.R. Birge et.al. J. Phys. Chem. B 1999,103, 10746
Femto-second Spectroscopic Measurements
| k >
| j >
Isomerization coordinate, )cc( 1211
Quantum interference of molecular wavepackets associated with indistinguishable pathways to the same
target state
Quantum interference of indistinguishable pathways to the same target state
x
O. Nairz, M. Arndt and A. Zeilinger Am. J. Phys. 71, 319, 2003
| j >
| k >
| xi >
| xf >
Bichromatic coherent-control(Weak-field limit)
Ground vibrational state
First Excited Vibrational State
Bichromatic coherent-control
Pul
se R
elat
ive
Pha
ses
Pulse Relative Intensities
Bichromatic coherent-control
Pul
se R
elat
ive
Pha
ses
Pulse Relative Intensities
Bichromatic coherent-control
Pul
se R
elat
ive
Pha
ses
Chirped Pump Pulses (Wigner transformation forms)
CR =
CR=
Bichirped Coherent Control
Positively Chirped Pulse (PC)
Negatively Chirped Pulse (NC)
Excited State S1
Ground State S0
cis trans
Exact Quantum Dynamics Simulations (t=218 fs, CR=212 fs2)
)fs35FWHM(nm500
Excited State S1
Ground State S0
cis trans
Exact Quantum Dynamics Simulations (t=218 fs, CR=-146 fs2)
)fs35FWHM(nm500
Energy
Reaction coordinate
S1
NC:
PC:
Impulsive Stimulated Raman Scattering
θ
Pul
se R
elat
ive
Pha
ses
Pulse Relative Intensities
Bichirped Coherent Control
Bichirped Coherent Control
Pul
se R
elat
ive
Pha
ses
Pulse Relative Intensities
Bichirped Coherent Control
Pulse Relative Intensities
Pul
se R
elat
ive
Pha
ses
Conclusions
We have shown that the photoisomerization of rhodopsin can be controlled by changing the coherence properties of the initial state in accord with a coherent control scenario that entails two femtosecond chirped pulses.
We have shown that the underlying physics involves controlling the dynamics of a subcomponent of the system (the photoinduced rotation along the C11-C12 bond) in the presence of intrinsic decoherence induced by the vibronic activity.
Extensive control has been demonstrated, despite the ultrafast intrinsic decoherence phenomena, providing results of broad theoretical and experimental interest.
QM/MM Investigation of the Primary Event in Vision
Jose A. Gascon and Victor S. Batista
Yale University, Department of Chemistry
(Submitted to JACS)
1F88, Palczewski et. al., Science 289, 739, 2000
Boundary C-Cof Lys296
ONIOM QM/MM B3LYP/631G*:Amber
QM Layer (red): 54-atoms MM Layer (red): 5118-atoms
EONIOM =EMM,full+EQM,red -EEMM,red
Reaction Path: negative-rotation
Energy Storage
Reaction Energy Profile: QM/MM ONIOM-EE (B3LYP/6-31G*:Amber)
*Exp Value :
Dihedral angle
11-cis rhodopsin
all-trans bathorhodopsin
Intermediate conformation
11-cis rhodopsin
all-trans bathorhodopsin
Intermediate conformation
Isomerization Process
C12 C11
N
H2O
Glu113
C13
Superposition of Rhodopsin and Bathorhodopsin in the Binding-Pocket:
Storage of Strain-Energy
Charge-Separation Mechanism
Reorientation of Polarized Bonds
HH
Energy Storage[QM/MM ONIOM-EE (B3LYP/6-31G*:Amber)]
Energy Storage[QM/MM ONIOM-ME(B3LYP/6-31G*:Amber)]-
Electrostatic Contribution of Individual Residues
Electrostatic Contribution to the Total Energy Storage 62%
TD-DFT Electronic ExcitationsONIOM-EE (TD-B3LYP/6-31G*:Amber)
E rhod. E
TD-B3LYP//B3LYP/6-31G*:Amber
CASPT2//CASSCF/6-31G*:Amber
E batho.
Experimental
Values in kcal/mol
63.5
64.1
57.4
60.3 3.2
54.0 3.4
Conclusions
We have shown that the ONIOM-EE (B3LYP/6-31G*:Amber) level of theory, in conjunction with high-resolution structural data, predicts the energy storage through isomerization, in agreement with experiments.
We have shown that structural distortions account for 40% of the energy stored, while the remaining 60 % is electrostatic energy due to stretching of the salt-bridge between the protonated Schiff-base and the Glu113 counterion.
We have shown that the salt-bridge stretching mechanism involves reorientation of polarized bonds due to torsion of the polyene chain at the linkage to Lys296, without displacing the linkage relative to Glu113 or redistributing charges within the chromophore
Conclusions (cont.)
We have demonstrated that a hydrogen-bonded water molecule, consistently found by X-ray crystallographic studies, can assist the salt-bridge stretching process by stabilizing the reorientation of polarized bonds.
We have shown that the absence of Wat2b, however, does not alter the overall structural rearrangements and increases the total energy storage in 1 kcal/mol.
We have demonstrated that the predominant electrostatic contributions to the total energy storage result from the interaction of the protonated Schiff-based retinyl chromophore with four surrounding polar residues and a hydrogen bonded water molecule.
We have shown that the ONIOM-EE (TD-B3LYP/6-31G*:Amber//B3LYP/6-31G:Amber) level of theory, predicts vertical excitation energy shifts in quantitative agreement with experiments, while the individual excitations of rhodopsin and bathorhodopsin are overestimated by 10%.
Funding Agencies
• Yale University Start-up Package• Yale University F. Warren Hellman Family
Fellowship• Yale University Rudolph J. Anderson Fellowship• American Chemical Society (PRF – Type G)• Research Corporation (Innovations Programs)• NSF Career Program