SESSION 3: MECHANICAL, THERMAL, AND CHEMICAL STABILITY OF MOFS

Effect of Temperature and Pressure on Structural and Mechanical Properties of MOFs from Quantum-Mechanical Calculations

Department of Chemistry, University of Torino, via Giuria 5, 10125, Torino, Italy

Keywords: elastic constants, quasi-harmonic approximation, shear instability, thermal expansion

Quantum-mechanical calculations based on the density functional theory (DFT) represent an effective mean to the determination and atomistic rationalization of many properties of materials. In recent years, much effort has gone in the development of effective and robust algorithms for the description of advanced properties of materials, and in their implementation into general-purpose public codes.

Here, I focus on the inclusion of pressure and temperature effects on structural, mechanical and thermodynamic properties of materials from DFT calculations. More specifically, I discuss recent progresses and open challenges of the application of such methodologies to the description of two classes of materials: molecular crystals and MOFs. These soft systems are held together by a variety of different chemical interactions (including weak ones), which need a balanced description, and are often characterized by alarge number of atoms per cell.

In this contribution, I review some of the methodologies that I have implemented into the public CRYSTAL program^[1-2] to include pressure and thermal effects (beyond the harmonic approximation) on computedproperties of solids^[3-4]. Examples will be given on the application of these methods to molecular crystals^[5-6] and MOFs^[7-9].

Figure 1. Left panel: Evolution with pressure of the mechanical anisotropy of ZIF-8. Right panel: structural andmechanical response of MOF-5 to pressure and temperature.

[1] R. Dovesi, A. Erba, et al., WIREs Comput. Mol. Sci., e1360, 2018
[2] A. Erba, J. Baima, et al., J. Chem. Theory Comput., 13, 5019, 2017
[3] A. Erba, J. Chem. Phys., 141, 124115, 2014
[4] A. Erba, A. Mahmoud, et al., J. Chem. Phys., 140, 124703, 2014
[5] A. Erba, J. Maul and B. Civalleri, Chem. Commun., 52, 1820, 2016
[6] M. Ruggiero, A. Zeitler and A. Erba, Chem. Commun., 53, 3781, 2017
[7] W. Zhang, J. Maul, et al., J. Phys. Chem. C, 122, 27442, 2018
[8] J. Maul, M.R. Ryder, et al., Phys. Rev. B., 99, 014102, 2019
[9] M.R. Ryder, J. Maul, et al., Adv. Theor. Simul., in preparation, 2019