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Conservation of Angular Momentum in Direct Nonadiabatic Dynamics
Yinan Shu1, Linyao Zhang1,2, Zoltán Varga1
1Department of Chemistry and Supercomputing Institute , University of Minnesota , Minneapolis , Minnesota 55455-0431 , United States.
The Journal of Physical Chemistry Letters
|January 21, 2020
Summary
Direct nonadiabatic dynamics calculations can now conserve angular momentum and center of mass. A new projection operator method corrects nonadiabatic couplings (NACs) in mixed quantum-classical simulations.
Area of Science:
- Quantum chemistry
- Chemical dynamics
- Computational physics
Background:
- Direct nonadiabatic dynamics simulates processes across multiple electronic states.
- It offers user-friendly calculations of energies, gradients, and nonadiabatic couplings (NACs).
- Existing methods often fail to conserve angular momentum and center of mass.
Purpose of the Study:
- To address the conservation issue in direct nonadiabatic dynamics.
- To improve the accuracy of mixed quantum-classical simulations.
Main Methods:
- Utilized direct dynamics approach.
- Employed electronic structure calculations for energies, gradients, and NACs.
- Developed and applied a projection operator method to modify NACs.
Main Results:
- The projection operator successfully removed translational and rotational components from NACs.
- Conservation of angular momentum and center of mass was restored.
- Validated the method in widely used algorithms like trajectory surface hopping.
Conclusions:
- The developed method enhances the reliability of direct nonadiabatic dynamics.
- This advancement improves simulations of molecular processes involving multiple electronic states.
- Enables more accurate modeling from small molecules to materials.
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