C A ANOMALIES, THERMOELECTRIC-POWER AND ELECTRONIC TOPOLOGICAL TRANSITIONS IN CD/

Thermoelectric power (TEP) measurements up to 6.9 GPa pressure;and the total energy calculations for the axial ratio (c/a) variation with co mpression were carried out for cadmium. We find two anomalies as compa red to a single anomaly observed in the experimental X-ray diffraction (XRD) data. The first anomaly at V/V-0 = 0.95 is due to electronic to pological transition (ETT) and correlates well with our TEP data, and with the anomaly observed in the existing resistivity data. The second anomaly at V/V-0 = 0.85 correlates well with the recent high-precisio n imaging plate-based XRD data. We attribute the 4d-orbital overlap, c oupled with transfer of electrons from d to s states as the cause of t his anomaly. This finding is in contrast to the existing understanding in zinc, where the c/a anomaly is attributed to the destruction of a giant Kohn anomaly by ETT. Non-destruction of the giant Kohn anomaly i n cadmium shows that the Fermi surface of Cd is different from that of Zn at high pressures. (C) 1998 Elsevier Science Ltd. All rights reser ved.