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The role of nuclear quantum effects in the relative stability of hexagonal and cubic ice.
J Chem Phys 2019; 151(14):144503JC

Abstract

At atmospheric pressure, hexagonal ice (Ih) is thermodynamically stable relative to cubic ice (Ic), although the magnitude and underlying physical origin of this stability difference are not well defined. Pure Ic crystals are not accessible experimentally, and hence computer simulations have often been used to interrogate the relative stabilities of Ih and Ic; however, these simulations are dominated by molecular interaction models that ignore the intramolecular flexibility of individual water molecules, do not describe intermolecular hydrogen-bonding with sufficient accuracy, or ignore the role of nuclear quantum effects (NQEs) such as zero-point energy. Here, we show that when comparing the relative stability of Ih and Ic using a flexible, anharmonic molecular interaction model, while also accurately accounting for NQEs, a new picture emerges: Ih is stabilized relative to Ic as a result of subtle differences in the intramolecular geometries and intermolecular interactions of water molecules which are modulated by NQEs. Our simulations hence suggest that NQEs are a major contributor to the stabilization of Ih under terrestrial conditions and thus contribute to the well-known hexagonal (sixfold) symmetry of ice crystals.

Authors+Show Affiliations

Department of Chemistry and Centre for Scientific Computing, University of Warwick, Coventry CV4 7AL, United Kingdom.Department of Physics and Centre for Scientific Computing, University of Warwick, Coventry CV4 7AL, United Kingdom.Department of Chemistry and Centre for Scientific Computing, University of Warwick, Coventry CV4 7AL, United Kingdom.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31615225

Citation

Buxton, Samuel J., et al. "The Role of Nuclear Quantum Effects in the Relative Stability of Hexagonal and Cubic Ice." The Journal of Chemical Physics, vol. 151, no. 14, 2019, p. 144503.
Buxton SJ, Quigley D, Habershon S. The role of nuclear quantum effects in the relative stability of hexagonal and cubic ice. J Chem Phys. 2019;151(14):144503.
Buxton, S. J., Quigley, D., & Habershon, S. (2019). The role of nuclear quantum effects in the relative stability of hexagonal and cubic ice. The Journal of Chemical Physics, 151(14), p. 144503. doi:10.1063/1.5123992.
Buxton SJ, Quigley D, Habershon S. The Role of Nuclear Quantum Effects in the Relative Stability of Hexagonal and Cubic Ice. J Chem Phys. 2019 Oct 14;151(14):144503. PubMed PMID: 31615225.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The role of nuclear quantum effects in the relative stability of hexagonal and cubic ice. AU - Buxton,Samuel J, AU - Quigley,David, AU - Habershon,Scott, PY - 2019/10/17/entrez PY - 2019/10/17/pubmed PY - 2019/10/17/medline SP - 144503 EP - 144503 JF - The Journal of chemical physics JO - J Chem Phys VL - 151 IS - 14 N2 - At atmospheric pressure, hexagonal ice (Ih) is thermodynamically stable relative to cubic ice (Ic), although the magnitude and underlying physical origin of this stability difference are not well defined. Pure Ic crystals are not accessible experimentally, and hence computer simulations have often been used to interrogate the relative stabilities of Ih and Ic; however, these simulations are dominated by molecular interaction models that ignore the intramolecular flexibility of individual water molecules, do not describe intermolecular hydrogen-bonding with sufficient accuracy, or ignore the role of nuclear quantum effects (NQEs) such as zero-point energy. Here, we show that when comparing the relative stability of Ih and Ic using a flexible, anharmonic molecular interaction model, while also accurately accounting for NQEs, a new picture emerges: Ih is stabilized relative to Ic as a result of subtle differences in the intramolecular geometries and intermolecular interactions of water molecules which are modulated by NQEs. Our simulations hence suggest that NQEs are a major contributor to the stabilization of Ih under terrestrial conditions and thus contribute to the well-known hexagonal (sixfold) symmetry of ice crystals. SN - 1089-7690 UR - https://www.unboundmedicine.com/medline/citation/31615225/The_role_of_nuclear_quantum_effects_in_the_relative_stability_of_hexagonal_and_cubic_ice L2 - https://dx.doi.org/10.1063/1.5123992 DB - PRIME DP - Unbound Medicine ER -