Approximate reconstruction of torsional potential energy surface based on voronoi tessellation

Chengming He, Yicheng Chi, Peng Zhang

Research output: Journal article publicationConference articleAcademic researchpeer-review

Abstract

Torsional modes within a complex molecule containing various functional groups are often strongly coupled so that the harmonic approximation and one-dimensional torsional treatment are inaccurate to evaluate their partition functions. A family of multi-structural approximation methods have been proposed and applied in recent years to deal with the torsional anharmonicity. However, these methods approximate the exact "almost periodic"potential energy as a summation of local periodic functions with symmetric barrier positions and heights. In the present theoretical study, we illustrated that the approximation is inaccurate when torsional modes present non-uniformly distributed local minima. Thereby, we proposed an improved method to reconstruct approximate potential to replace the periodic potential by using information of the local minima and their Voronoi tessellation. First, we established asymmetric barrier heights by introducing two periodicity parameters and assuming that the exact barrier positions are at the boundaries of Voronoi cells. Second, we used multiplicatively weighted Voronoi tessellation to refine the barrier heights and positions by defining a structure-related distance metric. The proposed method has been tested for a few higher-dimensional cases, all of which show promising improved accuracy.

Original languageEnglish
Pages (from-to)757-766
Number of pages10
JournalProceedings of the Combustion Institute
Volume38
Issue number1
Early online date6 Oct 2020
DOIs
Publication statusPublished - 2021
Event38th International Symposium on Combustion, 2021 - Adelaide, Australia
Duration: 24 Jan 202129 Jan 2021

Keywords

  • Almost periodic function
  • Multi-structural approximation
  • Partition function
  • Torsional anharmonicity
  • Voronoi tessellation

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Mechanical Engineering
  • Physical and Theoretical Chemistry

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