The Wolf method applied to the type I methane and carbon dioxide gas hydrates

Abstract

The Wolf method [42] is introduced to handle long-range electrostatic interactions as a viable alternative to the most common methods, i.e., the Ewald Sum and its modifications (PPPM, PME and SPME), the Reaction Field method, and the Lekner technique for predicting the structure of type I clathrate hydrates. In comparison with the Ewald Sum family, it is computationally more time-saving and mathematically much simpler. It is also physically more meaningful than the Ewald Sum for disordered systems, liquids and crystals. In comparison with the Reaction Field method, it does not require the calculation of the dielectric constant during the simulation. The computational cost of the Wolf method is also much less than the Lekner method. NPT and NVT ensemble Monte Carlo simulations are performed to calculate energetic and structural properties of CH4 and CO2 gas hydrates at formation pressures and temperatures. The optimum values of the control parameters employed in the Wolf method are evaluated and the criteria used for the calculations are discussed. Finally, the results are compared with several simulation results and experimental data and satisfactory agreement is achieved.