Molecular Dynamic Simulations of Clathrate Hydrate Structures I: Lattice Constant and Thermal Expansion

E Heidaryan and PD Pessoa and MDR Fuentes, JOURNAL OF LOW TEMPERATURE PHYSICS, 207, 227-240 (2022).

DOI: 10.1007/s10909-022-02725-9

Molecular dynamic (MD) simulations of hydrates of methane (CH4) and carbon dioxide (CO2) were carried out. The force fields TIP4P/2005, OPLS-UA, and TraPPE, were used. The lattice constant and thermal expansion coefficient were obtained as a function of temperature. Considering the results of the current simulations and experimental literature data, a simple, meaningful polynomial (a function of temperature) was used to fit the obtained lattice constants from 0 to 283.15 K. The derivative structural property of the isobaric thermal expansion coefficient was calculated from fluctuation through MD simulations. While failing to capture the true behavior at low temperatures (i.e., less than 100 K), the MD simulation results of lattice constants and isobaric thermal expansion coefficients are consistent at higher temperatures, which is the most important situation for practical applications of hydrates as energy source or gas storage medium.

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