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Single-Hessian thawed Gaussian approximation.

Tomislav Begušić1, Manuel Cordova1, Jiří Vaníček1

  • 1Laboratory of Theoretical Physical Chemistry, Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.

The Journal of Chemical Physics
|April 22, 2019
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Summary
This summary is machine-generated.

We introduce a computationally efficient single-Hessian thawed Gaussian approximation for calculating molecular spectra. This method offers accuracy comparable to more expensive techniques while conserving energy exactly.

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Area of Science:

  • Quantum chemistry
  • Spectroscopy
  • Computational physics

Background:

  • On-the-fly ab initio semiclassical calculations of molecular spectra are computationally intensive.
  • Existing methods like global harmonic schemes may lack accuracy for complex systems.

Purpose of the Study:

  • To develop a computationally efficient approximation for ab initio semiclassical calculations.
  • To reduce the computational cost of molecular spectra simulations.

Main Methods:

  • Proposing the single-Hessian thawed Gaussian approximation.
  • Approximating the potential energy Hessian with a constant matrix along classical trajectories.
  • Comparing results with exact quantum and experimental spectra.

Main Results:

  • The single-Hessian method achieves accuracy comparable to the more expensive thawed Gaussian approximation.
  • It significantly outperforms global harmonic schemes.
  • The method conserves energy exactly and can be mapped to a time-independent classical Hamiltonian.

Conclusions:

  • The single-Hessian thawed Gaussian approximation is an effective and efficient method for molecular spectra calculations.
  • It provides a good balance between accuracy and computational cost.
  • This approach facilitates faster prefactor calculations in semiclassical simulations.