The low frequency vibrations in clathrate hydrates

Abstract

The mechanism for the unexpectedly strong interactions between the guest and lattice vibrations in clathrate hydrates is revealed from molecular dynamics and lattice dynamics calculations on model systems. It is shown that the vibrational couplings are the result of avoided crossings of the enclathrated guest localized rattling modes with the host lattice acoustic phonon branches of the same symmetry. Through these couplings, energy can be exchanged between the host lattice and the guest vibrations and lead to the anomalous glasslike behavior in the thermal conductivity of gas hydrates.