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Exact non-adiabatic coupling vectors for the time-dependent density functional based tight-binding method.

Thomas A Niehaus1

  • 1University Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France.

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|February 8, 2023
PubMed
Summary
This summary is machine-generated.

We present a new method for calculating non-adiabatic coupling vectors in time-dependent density functional theory based tight-binding (TD-DFTB) simulations. This approach accurately captures electronic excited states and Berry phase, enabling reliable molecular dynamics for large systems.

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Area of Science:

  • Computational Chemistry
  • Quantum Mechanics
  • Theoretical Physics

Background:

  • Non-adiabatic coupling vectors are crucial for understanding excited-state dynamics.
  • Previous methods often neglected orbital relaxation effects or were computationally expensive.
  • Accurate simulations are needed for complex molecular systems.

Purpose of the Study:

  • To implement and validate non-adiabatic coupling vectors within the TD-DFTB framework.
  • To include orbital relaxation effects and range-separated functionals.
  • To enable accurate non-adiabatic molecular dynamics for large systems.

Main Methods:

  • Development of non-adiabatic coupling vector calculations for TD-DFTB.
  • Inclusion of orbital relaxation effects.
  • Use of range-separated exchange-correlation functionals.
  • Benchmark calculations against first-principles TD-DFT.

Main Results:

  • The TD-DFTB method with orbital relaxation provides accurate non-adiabatic couplings.
  • Non-adiabatic couplings show significant dependence on the chosen functional.
  • The method accurately reproduces the Berry phase around conical intersections.
  • The approach is suitable for simulating large molecular systems.

Conclusions:

  • The developed TD-DFTB method offers a computationally efficient and accurate way to study non-adiabatic dynamics.
  • This work paves the way for reliable non-adiabatic molecular dynamics simulations of large systems.
  • The inclusion of orbital relaxation and accurate Berry phase calculation are key advancements.