Alavi Saman, Ripmeester J A, Klug D D
Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada.
J Chem Phys. 2006 Sep 14;125(10):104501. doi: 10.1063/1.2238864.
Molecular dynamics simulations are used to study the stability of structure H (sH) clathrate hydrates with the rare gases Ne, Ar, Kr, and Xe. Simulations on a 3 x 3 x 3 sH unit cell replica are performed at ambient pressure at 40 and 100 K temperatures. The small and medium (s+m) cages of the sH unit cell are assigned rare gas guest occupancies of 1 and for large (l) cages guest occupancies of 1-6 are considered. Radial distribution functions for guest pairs with occupancies in the l-l, l-(s+m), and (s+m)-(s+m) cages are presented. The unit cell volumes and configurational energies are studied as a function of large cage occupancy for the rare gases. Free energy calculations are carried out to determine the stability of clathrates for large cage occupancies at 100 K and 1 bar and 20 kbar pressures. These studies show that the most stable argon clathrate has five guests in the large cages. For krypton and xenon the most stable configurations have three and two guests in the large cages, respectively.
分子动力学模拟用于研究含有稀有气体氖、氩、氪和氙的结构H（sH）笼形水合物的稳定性。在40K和100K温度的环境压力下，对一个3×3×3的sH晶胞复制品进行了模拟。sH晶胞的中小（s+m）笼中稀有气体客体占有率设为1，对于大（l）笼，考虑客体占有率为1 - 6的情况。给出了在l - l、l -（s+m）和（s+m）-（s+m）笼中占有率的客体对的径向分布函数。研究了稀有气体的晶胞体积和构型能量随大笼占有率的变化。进行了自由能计算，以确定在100K、1巴和20千巴压力下大笼占有率时笼形水合物的稳定性。这些研究表明，最稳定的氩笼形水合物在大笼中有五个客体。对于氪和氙，最稳定的构型分别在大笼中有三个和两个客体。
