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Modelling temperature-dependent properties of polymorphic organic molecular crystals

Modelling temperature-dependent properties of polymorphic organic molecular crystals
Modelling temperature-dependent properties of polymorphic organic molecular crystals
We present a large-scale study of the temperature-dependence of structures, free energy differences and properties of polymorphic molecular organic crystals. Lattice-vibrational Gibbs free energy differences between 475 pairs of polymorphs of organic molecular crystals have been calculated at 0 K and at their respective melting points, using a highly accurate anisotropic multipole-based force field and including thermal expansion through the use of a (negative) thermal pressure. Re-ranking of the relative thermodynamic stability of the polymorphs in each pair indicates the possibility of an enantiotropic phase transition between the crystal structures, which occurs in 21% of the studied systems. While vibrational contributions to free energies can have a significant effect on thermodynamic stability, the impact of thermal expansion on polymorph free energy differences is generally very small. We also calculate thermal expansion coefficients for the 864 crystal structures and investigate the temperature-dependence of mechanical properties, and pairwise differences in these properties between polymorphs.
1463-9076
31132-31143
Nyman, Jonas
0feff679-4e4f-4205-9ef9-6a4458ff2fc9
Day, Graeme Matthew
e3be79ba-ad12-4461-b735-74d5c4355636
Nyman, Jonas
0feff679-4e4f-4205-9ef9-6a4458ff2fc9
Day, Graeme Matthew
e3be79ba-ad12-4461-b735-74d5c4355636

Nyman, Jonas and Day, Graeme Matthew (2016) Modelling temperature-dependent properties of polymorphic organic molecular crystals. Physical Chemistry Chemical Physics, 18, 31132-31143. (doi:10.1039/C6CP05447A).

Record type: Article

Abstract

We present a large-scale study of the temperature-dependence of structures, free energy differences and properties of polymorphic molecular organic crystals. Lattice-vibrational Gibbs free energy differences between 475 pairs of polymorphs of organic molecular crystals have been calculated at 0 K and at their respective melting points, using a highly accurate anisotropic multipole-based force field and including thermal expansion through the use of a (negative) thermal pressure. Re-ranking of the relative thermodynamic stability of the polymorphs in each pair indicates the possibility of an enantiotropic phase transition between the crystal structures, which occurs in 21% of the studied systems. While vibrational contributions to free energies can have a significant effect on thermodynamic stability, the impact of thermal expansion on polymorph free energy differences is generally very small. We also calculate thermal expansion coefficients for the 864 crystal structures and investigate the temperature-dependence of mechanical properties, and pairwise differences in these properties between polymorphs.

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Accepted/In Press date: 31 October 2016
e-pub ahead of print date: 31 October 2016
Organisations: Chemistry

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Local EPrints ID: 402185
URI: http://eprints.soton.ac.uk/id/eprint/402185
ISSN: 1463-9076
PURE UUID: 5155a2db-1d2f-4e58-932c-02c5a442394a
ORCID for Graeme Matthew Day: ORCID iD orcid.org/0000-0001-8396-2771

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Date deposited: 03 Nov 2016 13:31
Last modified: 07 Oct 2020 04:54

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Author: Jonas Nyman

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