Molecular dynamics of fluoromethane type I hydrates

Abstract

Fluorinated methane derivatives are small size molecules susceptible to be enclathrated inside type I water hydrate structure. These hydrates present a great interest due to the very high global warming potential of fluoromethanes. Nevertheless, their properties at microscopic scale have not been sufficiently investigated yet. In fact, there are scarce, if any, molecular dynamics simulations studies available in the literature. In the present work we have performed atomistic molecular dynamics simulations of fluoromethanes and their hydrates. OPLS-AA and TIP4P/ICE force fields were employed to model fluoromethanes and water, respectively. Liquid–vapor equilibrium simulations were performed to test OPLS-AA force field for fluorinated compounds. As results were not satisfactory, the molecular models were refined through the recalculation of atomic electric point charges. Then, molecular simulations were performed to study the three phase equilibrium of their hydrates, comparing with available experimental information.