Thermal expansion in dispersion-bound molecular crystals

Hsin Yu Ko, Robert A. Distasio, Biswajit Santra, Roberto Car

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

We explore how anharmonicity, nuclear quantum effects (NQE), many-body dispersion interactions, and Pauli repulsion influence thermal properties of dispersion-bound molecular crystals. Accounting for anharmonicity with ab initio molecular dynamics yields cell parameters accurate to within 2% of experiment for a set of pyridinelike molecular crystals at finite temperatures and pressures. From the experimental thermal expansion curve, we find that pyridine-I has a Debye temperature just above its melting point, indicating sizable NQE across the entire crystalline range of stability. We find that NQE lead to a substantial volume increase in pyridine-I (≈40% more than classical thermal expansion at 153 K) and attribute this to intermolecular Pauli repulsion promoted by intramolecular quantum fluctuations. When predicting delicate properties such as the thermal expansivity, we show that many-body dispersion interactions and more sophisticated density functional approximations improve the accuracy of the theoretical model.

Original languageEnglish (US)
Article number055603
JournalPhysical Review Materials
Volume2
Issue number5
DOIs
StatePublished - May 18 2018

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Physics and Astronomy (miscellaneous)

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