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
ONIOM QM/MM B3LYP/631G*:Amber
QM Layer (red): 54-atoms MM Layer (red): 5118-atoms
EONIOM =EMM,full+EQM,red -EMM,red
Boundary Ca-Cd of Lys296
Reaction Path: negative-rotation
Reaction Energy Profile: QM/MM ONIOM-EE (B3LYP/6-31G*:Amber)
all-trans bathorhodopsin
Intermediate conformation
Exp Value : *
11-cis rhodopsin
Energy Storage
Dihedral angle
Intermediate conformation
all-trans bathorhodopsin
11-cis rhodopsin
Isomerization Process
C13
H2O
C12 C11
N
Glu113
Superposition of Rhodopsin and Bathorhodopsin in
the Binding-Pocket: Storage of Strain-Energy
Charge-Separation Mechanism
Reorientation of Polarized Bonds
H
H
Electrostatic Contribution to the Total Energy Storage
62%
-
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
TD-DFT Electronic Excitations
ONIOM-EE (TD-B3LYP/6-31G*:Amber)
Values in kcal/mol
DE
rhod.
TD-B3LYP//B3LYP/6-31G*:Amber
63.5
CASPT2//CASSCF/6-31G*:Amber
64.1
Experimental
57.4
DE
batho.
DDE
60.3
3.2
54.0
3.4
Time-Sliced Simulations of Quantum Processes
Trotter Expansion
MP/SOFT Method
Wu,Y.; Batista, V.S. J. Chem. Phys. 118, 6720 (2003)
Wu,Y.; Batista, V.S. J. Chem. Phys. 119, 7606 (2003)
Wu,Y.; Batista, V.S. J. Chem. Phys. 121, 1676 (2004)
Chen, X., Wu,Y.; Batista, V.S. J. Chem. Phys. 122, 64102 (2005)
Wu,Y.; Herman, M.F.; Batista, V.S. J. Chem. Phys. 122, 114114 (2005)
Wu,Y.; Batista, V.S. J. Chem. Phys. (2006) 124, 224305
Chen, X.; Batista, V.S. J. Chem. Phys. (2006) 125, 124313
Chen, X.; Batista, V.S. J. Photochem. Photobiol. 190, 274-282 (2007)
Bichromatic coherent-control
(Weak-field limit)
Quantum interference of molecular wavepackets associated
with indistinguishable pathways to the same target state
|j>
|k>
Isomerization coordinate, (c11  c12)
Time dependent wavepacket undergoing nonadiabatic dynamics at the
conical intersection of S1/S0 potential energy surfaces
Chen X, Batista VS; J. Photochem. Photobiol. 190, 274-282 (2007)
Ground vibrational state
First Excited Vibrational State
Pulse Relative Phases
Bichromatic coherent-control
Pulse Relative Intensities
Pulse Relative Phases
Bichromatic coherent-control
Pulse Relative Intensities
Pulse Relative Phases
Bichromatic coherent-control
The Primary Step in Vision
cis/trans isomerization in visual rhodopsin
Flores SC and Batista VS, J. Phys. Chem. B (2004) 108: 6745-6749
Gascon JA, Batista VS, Biophys. J. (2004) 87:2931-29411
Gascon JA, Sproviero EM, Batista VS, J. Chem. Theor. Comput. (2005) 1:674-685
Gascon JA, Sproviero EM, Batista VS, Acc. Chem. Res. (2006) 39, 184-193
Chen X and Batista VB, J. Photochem. Photobiol. submitted (2007) 190, 274-282, 2007
Empirical model (Domcke, Stock)
Time dependent reactant population
MP/SOFT‡
TDSCF*
0.67
Ptrans(S0)
Pcis(S1)
Time, fs
‡Chen X, Batista VS;
*Flores
J. Photochem. Photobiol. submitted (2007)
SC and Batista VS, J. Phys. Chem. B (2004) 108: 6745-6749
Quantum interference of molecular wavepackets associated
with indistinguishable pathways to the same target state
Flores SC; Batista VS, J. Phys. Chem. B 108: 6745-6749 (2004)
Batista VS; Brumer P, Phys. Rev. Lett. 89, 143201 (2002)
|j>
|k>
Isomerization coordinate,  (c11  c12)
Quantum interference of indistinguishable
pathways to the same target state
x
| xi >
|j>
|k>
| xf >
O. Nairz, M. Arndt and A. Zeilinger Am. J. Phys. 71, 319 (2003)
Bichirped Coherent Control Scenario
Flores SC; Batista VS, J. Phys. Chem. B (2004) 108: 6745-6749
Chirped Pump Pulses (Wigner transformation forms)
CR =
CR=
Impulsive Stimulated Raman Scattering
Energy
S1
Reaction coordinate (Stretch. Coord.)
NC:
PC:
Exact Quantum Dynamics Simulations (t=218 fs, CR=212 fs2)
Excited State S1
  500nm (FWHM  35fs )
Ground State S0
cis
trans
Positively Chirped Pulse (PC), strong field
Exact Quantum Dynamics Simulations (t=218 fs, CR=-146 fs2)
Excited State S1
  500nm (FWHM  35fs )
Ground State S0
cis
trans
Negatively Chirped Pulse (NC), strong field
Pulse Relative Phases
Bichirped Coherent Control Maps (1.2 ps)
Pulse Relative Intensities
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.

Control over 5-10% product yields should be possible,
despite the ultrafast intrinsic decoherence phenomena,
providing results of broad theoretical and experimental
interest.
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 saltbridge 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/631G*: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%.
