Exploring vacancy defects in s-I clathrate hydrates

Abstract

This study investigates the role of vacancy defects in s-I clathrate hydrate structures, particularly in the presence of ethylene oxide (EO) molecules, through first-principles calculations. The structural properties, formation energies, and guest-host interactions of these vacancy defects were examined in both periodic systems and finite-size clusters. Our findings demonstrate that EO molecules significantly stabilize vacancy defects via hydrogen bonding, especially when forming double hydrogen bonds with dangling hydrogens (d-Hs) arising from the molecular vacancy defect. The encapsulation of EO in defect-free cages and its interaction with dangling oxygens (d-Os) were also analyzed, highlighting the superior stabilizing effect of double hydrogen bonds. These results provide new insights into the behavior of vacancy defects in hydrate structures and the potential role of polar guest molecules in enhancing defect stability and facilitating hydrate formation processes.