Hydrogen-bond vibrational and energetic dynamical properties in sI and sII clathrate hydrates and in ice Ih: Molecular dynamics insights

• Published in: The Journal of Chemical Physics
• Main Authors: Chakraborty, Somendra Nath, English, Niall J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: AIP Publishing 2015
• Subjects: Physical and Theoretical Chemistry; General Physics and Astronomy; Methane hydrate
• Online Access: http://dx.doi.org/10.1063/1.4932681; https://pubs.aip.org/aip/jcp/article-pdf/doi/10.1063/1.4932681/15503667/154504_1_online.pdf

Equilibrium molecular dynamics (MD) simulations have been performed on cubic (sI and sII) polymorphs of methane hydrate, and hexagonal ice (ice Ih), to study the dynamical properties of hydrogen-bond vibrations and hydrogen-bond self-energy. It was found that hydrogen-bond energies are greatest in magnitude in sI hydrates, followed by sII, and their energies are least in magnitude in ice Ih. This is consistent with recent MD-based findings on thermal conductivities for these various materials [N. J. English and J. S. Tse, Phys. Rev. Lett. 103, 015901 (2009)], in which the lower thermal conductivity of sI methane hydrate was rationalised in terms of more strained hydrogen-bond arrangements. Further, modes for vibration and energy-transfer via hydrogen bonds in sI hydrate were found to occur at higher frequencies vis-à-vis ice Ih and sII hydrate in both the water-librational and OH⋯H regions because of the more strained nature of hydrogen bonds therein.