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Fragmentation and transferability in Hirshfeld atom refinement.

Michał Chodkiewicz1, Sylwia Pawlędzio1, Magdalena Woińska1

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Summary
This summary is machine-generated.

A new fragmentation approach significantly speeds up Hirshfeld atom refinement (HAR) for large molecules, offering a computationally efficient method for accurate hydrogen atom positioning in X-ray crystallography.

Keywords:
Hirshfeld atom refinementfragmentationquantum crystallographytransferability

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Area of Science:

  • Crystallography and Structural Chemistry
  • Computational Chemistry
  • Materials Science

Background:

  • Hirshfeld atom refinement (HAR) provides accurate hydrogen atom parameters from X-ray diffraction data.
  • Standard HAR is computationally intensive, particularly for large molecules, due to wavefunction calculations.
  • Existing methods face challenges with polymeric and disordered systems.

Purpose of the Study:

  • To develop a computationally efficient alternative to standard Hirshfeld atom refinement (HAR).
  • To investigate the application of a fragmentation approach for accelerating HAR calculations.
  • To explore the utility of fragmentation for polymeric and disordered systems.

Main Methods:

  • A fragmentation approach was implemented to reduce computational cost in HAR.
  • Calculations were performed using a modified Olex2 suite with discamb2tsc and ORCA.
  • Load-balancing on multicore processors was employed to optimize computation time.

Main Results:

  • The fragmentation approach achieved an order of magnitude speedup for large organic molecules.
  • Metal-organic systems showed several-fold improvements in computation time with minor structural parameter differences.
  • Fragmentation provided effective solutions for polymeric and disordered systems.

Conclusions:

  • Fragmentation offers a computationally efficient and accurate method for Hirshfeld atom refinement (HAR).
  • This approach enhances the applicability of HAR to larger, polymeric, and disordered systems.
  • The method shows promise for improving transferable aspherical atom models (TAAM) and handling intermolecular interactions.