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Main Authors: Blech, Alexander, Ebeling, Raoul M. M., Heger, Marec, Koch, Christiane P., Reich, Daniel M.
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2407.17434
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author Blech, Alexander
Ebeling, Raoul M. M.
Heger, Marec
Koch, Christiane P.
Reich, Daniel M.
author_facet Blech, Alexander
Ebeling, Raoul M. M.
Heger, Marec
Koch, Christiane P.
Reich, Daniel M.
contents In molecular physics, it is often necessary to average over the orientation of molecules when calculating observables, in particular when modelling experiments in the liquid or gas phase. Evaluated in terms of Euler angles, this is closely related to integration over two- or three-dimensional unit spheres, a common problem discussed in numerical analysis. The computational cost of the integration depends significantly on the quadrature method, making the selection of an appropriate method crucial for the feasibility of simulations. After reviewing several classes of spherical quadrature methods in terms of their efficiency and error distribution, we derive guidelines for choosing the best quadrature method for orientation averages and illustrate these with three examples from chiral molecule physics. While Gauss quadratures allow for achieving numerically exact integration for a wide range of applications, other methods offer advantages in specific circumstances. Our guidelines can also by applied to higher-dimensional spherical domains and other geometries. We also present a Python package providing a flexible interface to a variety of quadrature methods.
format Preprint
id arxiv_https___arxiv_org_abs_2407_17434
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Numerical evaluation of orientation averages and its application to molecular physics
Blech, Alexander
Ebeling, Raoul M. M.
Heger, Marec
Koch, Christiane P.
Reich, Daniel M.
Computational Physics
Atomic Physics
Quantum Physics
In molecular physics, it is often necessary to average over the orientation of molecules when calculating observables, in particular when modelling experiments in the liquid or gas phase. Evaluated in terms of Euler angles, this is closely related to integration over two- or three-dimensional unit spheres, a common problem discussed in numerical analysis. The computational cost of the integration depends significantly on the quadrature method, making the selection of an appropriate method crucial for the feasibility of simulations. After reviewing several classes of spherical quadrature methods in terms of their efficiency and error distribution, we derive guidelines for choosing the best quadrature method for orientation averages and illustrate these with three examples from chiral molecule physics. While Gauss quadratures allow for achieving numerically exact integration for a wide range of applications, other methods offer advantages in specific circumstances. Our guidelines can also by applied to higher-dimensional spherical domains and other geometries. We also present a Python package providing a flexible interface to a variety of quadrature methods.
title Numerical evaluation of orientation averages and its application to molecular physics
topic Computational Physics
Atomic Physics
Quantum Physics
url https://arxiv.org/abs/2407.17434