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Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry
Published on: April 8, 2020
Towards converging non-adiabatic direct dynamics calculations using frozen-width variational gaussian product basis
David Mendive-Tapia1, Benjamin Lasorne, Graham A Worth
1Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom.
The Journal of Chemical Physics
|December 20, 2012
Summary
This study introduces a variational method for quantum dynamics, balancing accuracy and computational cost in modeling molecular radiationless decay. The approach accurately captures wavepacket motion and population transfer during excited-state decay processes.
Area of Science:
- Quantum dynamics
- Computational chemistry
- Molecular spectroscopy
Background:
- Radiationless decay is crucial for understanding excited-state molecular processes.
- Conical intersections play a key role in efficient non-adiabatic transitions.
- Accurate quantum dynamics simulations are computationally demanding.
Purpose of the Study:
- To investigate the convergence of quantum dynamics calculations using coupled variationally optimized Gaussian product basis functions.
- To model the radiationless decay of fulvene as a benchmark system.
- To assess the accuracy and computational efficiency of the proposed method.
Main Methods:
- Direct dynamics-variational multi-configuration Gaussian (DD-vMCG) method.
- Calculation of molecular potential energy surfaces on-the-fly.
- Modeling wavepacket motion on excited-state surfaces through conical intersections.
Main Results:
- The DD-vMCG method demonstrates convergence for quantum dynamics.
- Accurate modeling of fulvene's radiationless decay from S(1) to S(0) state.
- Monitoring of conical intersection seam sampling and population transfer dynamics.
Conclusions:
- The fully variational DD-vMCG approach offers a balance between accuracy and computational cost.
- This method provides a viable alternative to grid-based and surface-hopping techniques for non-adiabatic molecular quantum dynamics.
- The approach is suitable for molecules of comparable sizes to fulvene.
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