title: Free-energy calculation of structure-H hydrates.
abstract: A molecular-dynamics (MD) simulation of structure-H hydrates was performed under constant pressure and temperature with 6120 TIP4P water molecules, 900 OPLS-UA methane molecules, and 180 large molecular guest substance (LMGS) molecules. The LMGS molecules were represented in the form of a one-site Lennard-Jones (LJ) model using the LJ parameters sigma and epsilon. In order to clarify the thermodynamic stability of structure-H hydrates, we calculated the free-energy difference, changing on the sigma and epsilon only of the LMGS molecules. In this simulation, stable crystals of structure-H hydrates and a minimum value of DeltaG were obtained at sigma approximately 6.2 A and large values of epsilon. All simulations were performed using the special-purpose computer hardware MDGRAPE-2.
authors.affiliation: Department of Mechanical Engineering, Keio University, Yokohama 223-8522, Japan.
authors.forename: Yamato
authors.initials: Y
authors.lastname: Okano
authors.forename: Kenji
authors.initials: K
authors.lastname: Yasuoka