Issue 23, 2016

Accurate force fields and methods for modelling organic molecular crystals at finite temperatures

Abstract

We present an assessment of the performance of several force fields for modelling intermolecular interactions in organic molecular crystals using the X23 benchmark set. The performance of the force fields is compared to several popular dispersion corrected density functional methods. In addition, we present our implementation of lattice vibrational free energy calculations in the quasi-harmonic approximation, using several methods to account for phonon dispersion. This allows us to also benchmark the force fields' reproduction of finite temperature crystal structures. The results demonstrate that anisotropic atom–atom multipole-based force fields can be as accurate as several popular DFT-D methods, but have errors 2–3 times larger than the current best DFT-D methods. The largest error in the examined force fields is a systematic underestimation of the (absolute) lattice energy.

Graphical abstract: Accurate force fields and methods for modelling organic molecular crystals at finite temperatures

Supplementary files

Article information

Article type
Paper
Submitted
05 Apr 2016
Accepted
17 May 2016
First published
17 May 2016
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2016,18, 15828-15837

Author version available

Accurate force fields and methods for modelling organic molecular crystals at finite temperatures

J. Nyman, O. S. Pundyke and G. M. Day, Phys. Chem. Chem. Phys., 2016, 18, 15828 DOI: 10.1039/C6CP02261H

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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