First-principles calculation on phase stability and metallization in GeH4 under pressure

Using a first-principles calculation, we investigated some possible structures of GeH4 similar to those of SiH4 investigated by Feng et al. [J. Feng, W. Grochala, T. Jaron, R. Hoffmann, A. Bergara, N.W. Aschcroft, Phys. Rev. Lett. 96 (2006) 017006] and determined their metallization pressures. It is found that GeH4 has different case with SiH4 and has lower metallization pressure. Structure T-2 in germane emerges as an enthalpically competitive structure over the pressure range 55-62 GPa. The metallization pressure for GeH4 with T-3 structure is about 50 GPa, which is much lower than that of 91 GPa assumed for the O-3 phase of SiH4, i.e. GeH4 could be easier to be metallized than SiH4. (c) 2007 Elsevier Ltd. All rights reserved.