Accurate force fields and methods for modelling organic molecular crystals at finite temperatures. Issue 23 (27th May 2016)

• Record Type: Journal Article
• Authors: Nyman, Jonas; Pundyke, Orla Sheehan; Day, Graeme M.
• Is Part Of: Physical chemistry chemical physics. Volume 18:Issue 23(2016)
• Page Start: 15828
• Page End: 15837
• Publication Date: 2016-05-27
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c6cp02261h
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : We assess a series of atom–atom force fields for lattice energy and free energy modelling of molecular organic crystals. 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.