Molecular dynamics simulations of ice and methane hydrate by means of the rotation coordinate TIP5P-Ewald model

Abstract

Molecular dynamics simulations are utilized to study the microwave heating of methane hydrate by the five-body rotation coordinate system with the TIP5P-Ewald model. The structure I of methane hydrate is constructed, and the ice and free methane or methane hydrate are exposed to microwave electric fields of 10 GHz. Provisional methane hydrate of the normal density and a temperature of 273 K is dynamically unstable and collapses after some periods of irradiation. The period of a collapse time is $1.7 \times 10^{6} \tau $ and the temperature increase is $\Delta T \cong 61$ deg, with the external electric field $3 \times 10^{7} \rm{V/cm}$ (i.e. 0.3 V/\AA) and $\tau = 1 \times 10^{-14}$ s. For the ice and free methane of the temperature 193 K and the pressure 1 atm, the system is stable while it is heated under microwave irradiation. About the temperature of 273 K, high density methane hydrate becomes stable, whereas the density of 0.93 g/cm$^{3}$ is marginally stable but is heated when microwaves are present. In the microwave device of 1,000 V/cm and the pressure 1 atm, the simulation of the ice and methane points to 1 s in the 100\% microwave efficiency.