MD Simulation of CO2-CH4 Mixed Hydrate on Crystal Structure and Stability

MD simulations are carried out on the sI CO(2)-CH(4) mixed hydrates in the constant-NVT and constant-NPT ensembles for the two cases of CO(2) occupancy. One is 75% called normal, the other is 87.5%. The simulations results show that the hydrate structure can be maintained both for the two hydrates over the temperature range of 0K to 300K. However, the equilibrium pressure, the potential energy and the MSDs of the atoms in H(2)O for the higher CO(2) ratio hydrates is larger than that of the normal CO(2) ratio hydrates, indicating that the normal mixed hydrates is more stable than the higher CO(2) occupancy mixed hydrate. These results are consistent with the present experimental results.