Pressure-induced behavior of the hydrogen-dominant compound SiH4(H2)2 from first-principles calculation

Abstract

The structural and electronic properties of the high pressure molecular compound SiH4(H2)2 have been calculated using density functional theory. We identify the molecular hydrogen positions within the face-centered cubic unit cell and further find that pressure-induced intermolecular interaction between SiH4 and H2 units plays an important role in stabilizing this new compound. The electronic structure is characterized by a wide band gap of 6.1 eV at 6.8 GPa, which closes with pressure and finally becomes metallic at 200 GPa due to electronic band overlap accompanied by a structure change. These findings have potential implications for understanding metallization and superconductivity in H2.