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Dynamic Electron Correlation Effects on the Ground State Potential Energy Surface of a Retinal Chromophore Model
Samer Gozem1, Mark Huntress1, Igor Schapiro1
1Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403, United States.
Investigating electron correlation in the retinal chromophore reveals significant reshaping of potential energy surfaces. This dynamic electron correlation impacts charge transfer and isomerization mechanisms in visual pigments.
Area of Science:
- Computational Chemistry
- Photochemistry
- Biophysics
Background:
- The retinal chromophore in visual pigments is crucial for light detection.
- Its potential energy surface has conical intersections and charge-transfer characteristics.
- Dynamic electron correlation is hypothesized to influence its reactivity.
Purpose of the Study:
- To investigate the impact of dynamic electron correlation on the retinal chromophore's potential energy surface.
- To model the retinal chromophore using the penta-2,4-dieniminium cation.
- To analyze how electron correlation affects isomerization pathways.
Main Methods:
- Calculations of the ground state CASSCF potential energy surface for three reaction paths.
- Inclusion of dynamic electron correlation using MRCISD, CASPT2, NEVPT2, and XMCQDPT2 methods.
- Mapping potential energy along bond length alternation and isomerization coordinates.
Main Results:
- Dynamic electron correlation stabilizes charge-transfer regions.
- Significant reshaping of the CASSCF potential energy surface was observed.
- A potential shift in the dominant isomerization mechanism is suggested.
Conclusions:
- Dynamic electron correlation is essential for accurately describing the retinal chromophore's electronic structure.
- Computational corrections alter the understanding of photoisomerization mechanisms in visual pigments.
- Further studies are needed to fully elucidate the impact on visual pigment function.
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