In the first part of this thesis, Molecular dynamics simulations are used to determine the hydrate lattice parameters for eight Structure I (CH 4 , C 2 H 6 , CO, CS, CH 4 + C 2 H 2 , CH 4 + C 2 H 4 , CH 4 + COS , and CH 4 + CS2) as a function of temperature. The simulated lattice parameters and the calculated linear thermal expansion coefficient are in good agreement with experimental data. In the second part of thesis, molecular dynamics simulations are performed for linear molecules CO, CS, CS 2 , OCS, and HCCH and nonlinear molecule C 2 H 4 in large cages of the structure I (sI) clathrate hydrate at different temperatures in the stability range to determine the angular distribution and dynamics of the guests in the large cages. When a guest molecule is placed in the oblate large sI clathrate hydrate cages, it rotates so that the long axis of the molecule is confined near the equatorial plane of the cage rather than axial regions. This non-uniform spatial distribution leads to anisotropic lineshapes in the solid-state NMR spectra of the guest species. We use the averaging of guest orientations in the cages during the MD simulation to calculate 13 C NMR powder lineshapes of the guests in the large cages. The length of the molecules and strength of intermolecular interactions of the guests with the cage water molecules are shown to be the important factors in determining the angular distribution and the mobility of the guests in the sI large cages.
