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Static and lattice vibrational energy differences between polymorphs

Static and lattice vibrational energy differences between polymorphs
Static and lattice vibrational energy differences between polymorphs
A computational study of 1061 experimentally determined crystal structures of 508 polymorphic organic molecules has been performed with state-of-the-art lattice energy minimisation methods, using a hybrid method that combines density functional theory intramolecular energies with an anisotropic atom–atom intermolecular model. Rigid molecule lattice dynamical calculations have also been performed to estimate the vibrational contributions to lattice free energies. Distributions of the differences in lattice energy, free energy, zero point energy, entropy and heat capacity between polymorphs are presented. Polymorphic lattice energy differences are typically very small: over half of polymorph pairs are separated by less than 2 kJ mol?1 and lattice energy differences exceed 7.2 kJ mol?1 in only 5% of cases. Unsurprisingly, vibrational contributions to polymorph free energy differences at ambient conditions are dominated by entropy differences. The distribution of vibrational energy differences is narrower than lattice energy differences, rarely exceeding 2 kJ mol?1. However, these relatively small vibrational free energy contributions are large enough to cause a re-ranking of polymorph stability below, or at, room temperature in 9% of the polymorph pairs
1466-8033
5154-5165
Day, Graeme M.
e3be79ba-ad12-4461-b735-74d5c4355636
Nyman, Jonas
0feff679-4e4f-4205-9ef9-6a4458ff2fc9
Day, Graeme M.
e3be79ba-ad12-4461-b735-74d5c4355636
Nyman, Jonas
0feff679-4e4f-4205-9ef9-6a4458ff2fc9

Day, Graeme M. and Nyman, Jonas (2015) Static and lattice vibrational energy differences between polymorphs. CrystEngComm, 17 (28), 5154-5165. (doi:10.1039/C5CE00045A).

Record type: Article

Abstract

A computational study of 1061 experimentally determined crystal structures of 508 polymorphic organic molecules has been performed with state-of-the-art lattice energy minimisation methods, using a hybrid method that combines density functional theory intramolecular energies with an anisotropic atom–atom intermolecular model. Rigid molecule lattice dynamical calculations have also been performed to estimate the vibrational contributions to lattice free energies. Distributions of the differences in lattice energy, free energy, zero point energy, entropy and heat capacity between polymorphs are presented. Polymorphic lattice energy differences are typically very small: over half of polymorph pairs are separated by less than 2 kJ mol?1 and lattice energy differences exceed 7.2 kJ mol?1 in only 5% of cases. Unsurprisingly, vibrational contributions to polymorph free energy differences at ambient conditions are dominated by entropy differences. The distribution of vibrational energy differences is narrower than lattice energy differences, rarely exceeding 2 kJ mol?1. However, these relatively small vibrational free energy contributions are large enough to cause a re-ranking of polymorph stability below, or at, room temperature in 9% of the polymorph pairs

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More information

Accepted/In Press date: 23 March 2015
e-pub ahead of print date: 23 March 2015
Published date: 28 July 2015
Organisations: Computational Systems Chemistry

Identifiers

Local EPrints ID: 376028
URI: http://eprints.soton.ac.uk/id/eprint/376028
ISSN: 1466-8033
PURE UUID: 8af9ee48-edcb-4fa9-846b-4a7571c5c574
ORCID for Graeme M. Day: ORCID iD orcid.org/0000-0001-8396-2771

Catalogue record

Date deposited: 23 Apr 2015 08:35
Last modified: 15 Sep 2021 01:59

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Contributors

Author: Graeme M. Day ORCID iD
Author: Jonas Nyman

University divisions

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