2001 Volume 42 Issue 11 Pages 2194-2200
The behavior of clathrate hydrate of structure I with and without enclathrated methane and xenon guests has been investigated at high pressure and wide temperature range using the quasiharmonic lattice dynamics approach up to absolute stability limits. The mechanical stability boundaries of the clathrate hydrate of structure I have been determined from the Born stability criteria via the calculations of the elastic constants at positive and negative pressures. For comparison the spinodals of the clathrate hydrates are calculated. It is found that in spite of weakness of interaction the enclathrated guests with host lattice the guest molecules contribute greatly to the stability of the hydrate framework structure.