THEORETICAL-ANALYSIS OF THE ISOSTRUCTURAL TRANSITION IN ZR AT 53-GPA

Recent diamond anvil x-ray diffraction measurements in Zr show a first-order isostructural transition at 53 GPa (V/V-0 = 0.68), beyond the known HCP to omega and omega to BCC transitions at 6.7 GPa and 33 GPa respectively. This transition has been attributed to the completion of s --> d electron transfer in Zr. Here, we report our ab initio band structure analysis of this transition. Our two-panel LMTO calculations (that also includes the 4p core states) rule out the completion of s --> d electron transfer up to V/V-0 = 0.55. Also our calculated room-temperature isotherm does not display van der Waals loop.