Theoretical high-pressure studies of Cs metal

We have studied the crystal structures of cesium metal 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 transformation sin Cs [Schwarz et al. Phys. Rev. Lett. 81, 2711 (1998)]. The calculated transition pressures agree well with the measured data. Also the computed axial c/a ratio for Cs-IV and Cs-VI is found to be in good agreement with experiment. Similarly the calculated a/b, c/d ratios as well as the three internal parameters for the Cs-V phase agrees ver well with measurement. The structural stability of different phases in Cs is also supported by canonical d-band model calculations.