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On the importance of anharmonicities and nuclear quantum effects in modelling the structural properties and thermal expansion of MOF-5

Aran Lamaire (UGent) , Jelle Wieme (UGent) , Sven Rogge (UGent) , Michel Waroquier (UGent) and Veronique Van Speybroeck (UGent)
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Abstract
In this article, we investigate the influence of anharmonicities and nuclear quantum effects (NQEs) in modelling the structural properties and thermal expansion of the empty MOF-5 metal-organic framework. To introduce NQEs in classical molecular dynamics simulations, two different methodologies are considered, comparing the approximate, but computationally cheap, method of generalised Langevin equation thermostatting to the more advanced, computationally demanding path integral molecular dynamics technique. For both methodologies, similar results were obtained for all the properties under investigation. The structural properties of MOF-5, probed by means of radial distribution functions (RDFs), show some distinct differences with respect to a classical description. Besides a broadening of the RDF peaks under the influence of quantum fluctuations, a different temperature dependence is also observed due to a dominant zero-point energy (ZPE) contribution. For the thermal expansion of MOF-5, by contrast, NQEs appear to be only of secondary importance with respect to an adequate modelling of the anharmonicities of the potential energy surface (PES), as demonstrated by the use of two differently parametrised force fields. Despite the small effect in the temperature dependence of the volume of MOF-5, NQEs do however significantly affect the absolute volume of MOF-5, in which the ZPE resulting from the intertwining of NQEs and anharmonicities plays a crucial role. A sufficiently accurate description of the PES is therefore prerequisite when modelling NQEs.
Keywords
METAL-ORGANIC FRAMEWORKS, FORCE-FIELD, DYNAMICS, WATER, INTEGRATORS, CHEMISTRY, QUICKFF, DESIGN

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Chicago
Lamaire, Aran, Jelle Wieme, Sven Rogge, Michel Waroquier, and Veronique Van Speybroeck. 2019. “On the Importance of Anharmonicities and Nuclear Quantum Effects in Modelling the Structural Properties and Thermal Expansion of MOF-5.” Journal of Chemical Physics 150 (9).
APA
Lamaire, A., Wieme, J., Rogge, S., Waroquier, M., & Van Speybroeck, V. (2019). On the importance of anharmonicities and nuclear quantum effects in modelling the structural properties and thermal expansion of MOF-5. JOURNAL OF CHEMICAL PHYSICS, 150(9).
Vancouver
1.
Lamaire A, Wieme J, Rogge S, Waroquier M, Van Speybroeck V. On the importance of anharmonicities and nuclear quantum effects in modelling the structural properties and thermal expansion of MOF-5. JOURNAL OF CHEMICAL PHYSICS. 2019;150(9).
MLA
Lamaire, Aran et al. “On the Importance of Anharmonicities and Nuclear Quantum Effects in Modelling the Structural Properties and Thermal Expansion of MOF-5.” JOURNAL OF CHEMICAL PHYSICS 150.9 (2019): n. pag. Print.
@article{8615952,
  abstract     = {In this article, we investigate the influence of anharmonicities and nuclear quantum effects (NQEs) in modelling the structural properties and thermal expansion of the empty MOF-5 metal-organic framework. To introduce NQEs in classical molecular dynamics simulations, two different methodologies are considered, comparing the approximate, but computationally cheap, method of generalised Langevin equation thermostatting to the more advanced, computationally demanding path integral molecular dynamics technique. For both methodologies, similar results were obtained for all the properties under investigation. The structural properties of MOF-5, probed by means of radial distribution functions (RDFs), show some distinct differences with respect to a classical description. Besides a broadening of the RDF peaks under the influence of quantum fluctuations, a different temperature dependence is also observed due to a dominant zero-point energy (ZPE) contribution. For the thermal expansion of MOF-5, by contrast, NQEs appear to be only of secondary importance with respect to an adequate modelling of the anharmonicities of the potential energy surface (PES), as demonstrated by the use of two differently parametrised force fields. Despite the small effect in the temperature dependence of the volume of MOF-5, NQEs do however significantly affect the absolute volume of MOF-5, in which the ZPE resulting from the intertwining of NQEs and anharmonicities plays a crucial role. A sufficiently accurate description of the PES is therefore prerequisite when modelling NQEs.},
  articleno    = {094503},
  author       = {Lamaire, Aran and Wieme, Jelle and Rogge, Sven and Waroquier, Michel and Van Speybroeck, Veronique},
  issn         = {0021-9606},
  journal      = {JOURNAL OF CHEMICAL PHYSICS},
  language     = {eng},
  number       = {9},
  pages        = {11},
  title        = {On the importance of anharmonicities and nuclear quantum effects in modelling the structural properties and thermal expansion of MOF-5},
  url          = {http://dx.doi.org/10.1063/1.5085649},
  volume       = {150},
  year         = {2019},
}

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