A MOLECULAR-DYNAMICS STUDY OF METHANE ENCAPSULATED IN DODECASIL 3C

This paper summarizes the results of a molecular dynamics study of the clathrate silicate dodecasil 3C with different methane fillings, whic h covered the influence of cavities on the behaviour of entrapped mole cules. The simulations treat all degrees of freedom of methane at room temperature. The dynamics of methane is influenced very little by use of a flexible silicate framework, as compared with use of a rigid one . The calculated infrared and Raman spectra show that two types of mol ecular environment can be clearly recognized from the vibrational beha viour of the molecules. Also, in the low-frequency region the rigid mo lecule motions are well differentiated. In small cages the molecules a re located near the centres of cages, whereas in large cages the molec ules move along the walls of the cavities while their orientation is n early free.