Overview of Molecular Dynamics Simulation of Natural Gas Hydrate at Nanoscale

Table 1

Structural parameters of three common types of hydrate [8].

Hydrate crystal structure	I		II		H
Crystal type	Cubic		Cubic		Hexagonal
Space group	Pm3n (no. 223)		Fd3m (no. 227)		P6/mmm (no. 191)
Lattice parameter
Number of waters per unit cell	46		136		34
Cavity	Small	Large	Small	Large	Small	Medium	Large
Number of cavities per unit cell	2	6	16	8	3	2	1
Average cavity radius (Å)	3.95	4.33	3.91	4.73	3.91	4.06	5.71
Coordination number	20	24	20	28	20	20	36