A theoretical study of the dissociation of the sI methane hydrate induced by an external electric field

Abstract

Molecular dynamics simulations in the equilibrium isobaric-isothermal (NPT) ensemble were used to examine the strength of an external electric field required to dissociate the methane hydrate sI structure. The water molecules were modeled using the four-site TIP4P/Ice analytical potential and methane was described as a simple Lennard-Jones interaction site. A series of simulations were performed at T = 260 K with P = 80 bars and at T = 285 K with P = 400 bars with an applied electric field ranging from 1.0 V nm(-1) to 5.0 V nm(-1). For both (T,P) conditions, applying a field greater than 1.5 V nm(-1) resulted in the orientation of the water molecules such that an ice Ih-type structure was formed, from which the methane was segregated. When the simulations were continued without the external field, the ice-like structures became disordered, resulting in two separate phases: gas methane and liquid water.