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Identifying pragmatic quasi-harmonic electronic structure approaches for modeling molecular crystal thermal expansion

Abstract

Quasi-harmonic approaches provide an economical route to modeling the temperature dependence of molecular crystal structures and properties. Several studies have demonstrated good performance of these models, at least for rigid molecules, when using fragment-based approaches with correlated wavefunction techniques. Many others have found success employing dispersion-corrected density functional theory (DFT). Here, a hierarchy of models in which the energies, geometries, and phonons are computed either with correlated methods or DFT are examined to identify which combinations produce useful predictions for properties such as the molar volume, enthalpy, and entropy as a function of temperature. The results demonstrate that refining DFT geometries and phonons with single-point energies based on dispersion-corrected second-order M{\o}ller-Plesset perturbation theory can provide clear improvements in the molar volumes and enthalpies compared to those obtained from DFT alone. Predicted entropies, which are governed by vibrational contributions, benefit less clearly from the hybrid schemes. Using these hybrid techniques, the room-temperature thermochemistry of acetaminophen (paracetamol) is predicted to address the discrepancy between two experimental sublimation enthalpy measurements.

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Publication details

The article was received on 26 Feb 2018, accepted on 05 Mar 2018 and first published on 05 Mar 2018


Article type: Paper
DOI: 10.1039/C8FD00048D
Citation: Faraday Discuss., 2018, Accepted Manuscript
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    Identifying pragmatic quasi-harmonic electronic structure approaches for modeling molecular crystal thermal expansion

    J. L. McKinley and G. J. O. Beran, Faraday Discuss., 2018, Accepted Manuscript , DOI: 10.1039/C8FD00048D

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