Quasi-Harmonic Lattice Dynamics of a Prototypical Metal–Organic Framework

Matthew R. Ryder, Jefferson Maul, Bartolomeo Civalleri, Alessandro Erba

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23 Scopus citations

Abstract

Quasi-harmonic lattice-dynamical calculations are performed to investigate the combined effect of temperature and pressure on the structural and mechanical properties of a prototypical metal–organic framework material: MOF-5. The softening upon compression of an (Formula presented.) phonon mode at the Γ point in the high-symmetry F (Formula presented.) structure is identified, which leads to a symmetry reduction and a group–subgroup phase transition to a low-symmetry F (Formula presented.) phase for compressions larger than 0.8%. The effect of the symmetry reduction on the equation-of-state of MOF-5 is investigated, which provides a static bulk modulus K reducing from 17 to 14 GPa and a corresponding change of (Formula presented.) (pressure derivative of K) from positive to negative. The effect of pressure on the negative thermal expansion of the framework and on its mechanical response is analyzed. The evolution of the mechanical anisotropy of MOF-5 as a function of pressure is also determined, which allows identifying the occurrence of a shear-induced mechanical instability at 0.45 GPa.

Original languageEnglish
Article number1900093
JournalAdvanced Theory and Simulations
Volume2
Issue number11
DOIs
StatePublished - Nov 1 2019

Funding

M.R.R. acknowledges the U.S. Department of Energy Office of Science (Basic Energy Sciences) for research funding and the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under Contract No. DE-AC02-05CH11231 for access to supercomputing resources. M.R.R. would also like to thank Prof. Jin-Chong Tan for a discussion during the early stages of the work and the Engineering and Physical Sciences Research Council (EPSRC) for a Doctoral Prize Fellowship (EP/N509711/1) and the Rutherford Appleton Laboratory (RAL) for access to the SCARF cluster and additional computing resources. A.E. and J.M. thank the University of Torino and the Compagnia di San Paolo for funding (CSTO169372). M.R.R. acknowledges the U.S. Department of Energy Office of Science (Basic Energy Sciences) for research funding and the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under Contract No. DE‐AC02‐05CH11231 for access to supercomputing resources. M.R.R. would also like to thank Prof. Jin‐Chong Tan for a discussion during the early stages of the work and the Engineering and Physical Sciences Research Council (EPSRC) for a Doctoral Prize Fellowship (EP/N509711/1) and the Rutherford Appleton Laboratory (RAL) for access to the SCARF cluster and additional computing resources. A.E. and J.M. thank the University of Torino and the Compagnia di San Paolo for funding (CSTO169372).

Keywords

  • CRYSTAL code
  • mechanical softening upon compression
  • negative thermal expansion

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