Theoretical Prediction of Maximum Number of Methane Molecule Accommodation in Unit Cages of S-I Clathrate Structure

Abstract

Density Functional Theory (DFT) based simulations have been performed to determine maximum possible number of methane molecule accommodation in unit cages of methane hydrate structure-I (S-I). Interaction energy, encapsulation energy and incremental encapsulation energy are calculated using B3LYP functional and 6-31+G(d) basis set. Nuclear magnetic resonance and Raman spectroscopy of one methane encapsulated are predicted at B3LYP/6-31G(d) level for 5¹²6² hydrate cage. Maximum one methane molecule accommodation both in 5¹² and 5¹²6² cage is possible as per B3LYP/6-31+G(d) calculations. Theoretically predicted maximum number of methane molecule accommodation, NMR and Raman spectra are in good agreement with experimental results.

Keywords: Density Functional Theory, Interaction energy, Incremental encapsulation energy