Theoretical high-pressure studies of caesium hydride

We have investigated the alkali hydrides theoretically under high compressions by means of first-principles self-consistent total-energy calculations within the local-density approximation using the full-potential linear-muffin-tin-orbital (FPLMTO) method. Our results confirm the recent high-pressure experimental observations of crystallographic phase transformations in CsH (Ghandehari K, Luo H, Ruoff A L, Trail S S and DiSalvo F J 1995 Phys. Rev. Lett. 74 2264). The calculated transition pressures for the occurrence of the CsCl and CrB crystal structures as well as the associated theoretical volume changes agree with the experimental data. We also predict a similar high-pressure behaviour for RbH and KH but not for NaH and LiH.