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Efficient computation of adiabatic electronic populations in multi-mode vibronic systems: theory, implementation, and
Behnam Nikoobakht1, Horst Köppel, Etienne Gindensperger
1Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, INF 229, D-69120 Heidelberg, Germany.
This study introduces an effective-mode formalism to efficiently calculate adiabatic electronic populations in multi-mode vibronic systems. The hierarchy-of-modes approach significantly speeds up computations, enabling accurate dynamics studies.
Area of Science:
- Computational Chemistry
- Quantum Dynamics
- Spectroscopy
Background:
- Vibronic systems involve coupled electronic and vibrational motions.
- Accurate computation of adiabatic electronic populations is crucial for understanding molecular dynamics.
- Existing methods can be computationally intensive for multi-mode systems.
Purpose of the Study:
- To develop and apply an efficient effective-mode formalism for computing adiabatic electronic populations.
- To investigate the speed-up and accuracy of the hierarchy-of-modes approximation.
- To study the vibronic dynamics of pyrazine-type models.
Main Methods:
- Application of an effective-mode formalism using two variants.
- Numerical exact calculation of wave functions and populations using effective modes as a basis.
- Utilization of the hierarchy-of-modes formalism as an approximation scheme.
Main Results:
- The effective-mode formalism enables the computation of adiabatic populations.
- The hierarchy-of-modes formalism provides accurate results with 7-10 hierarchy members.
- Computational speed-up of 1-3 orders of magnitude is achieved for propagation and population computation.
- The method was applied to pyrazine-type models with varying coupling strengths and numerous bath modes.
Conclusions:
- The effective-mode formalism is a powerful tool for studying multi-mode vibronic systems.
- The hierarchy-of-modes approximation offers a significant computational advantage.
- This approach facilitates detailed investigations into complex molecular dynamics.
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