Electronic structure and metalization of a silane-hydrogen system under high pressure investigated using density functional and GW calculations

Abstract

We have computed the electronic structure and the vibrational properties of the recently discovered hydrogen-rich compound silane-hydrogen $[{\text{SiH}}_{4}{({\text{H}}_{2})}_{2}]$ from first principles, using density-functional theory. We have also studied the metallization under pressure of ${\text{SiH}}_{4}{({\text{H}}_{2})}_{2}$ by the GW approximation, and obtained that the metallization occurs around 164 GPa, whereas the standard GGA calculations predict a metallization pressure around 145 GPa. Our results are compared with the recent experiment data of Strobel et al. [Phys. Rev. Lett. 103, 065701 (2009)] and Wang et al. [Proc. Natl. Acad. Sci. USA. 106, 14763 (2009)] and it is found that our calculated value of the metallization pressure is higher than the proposed experimental data. Some possible reasons for such a discrepancy are discussed in the text.