A pseudopotential calculation of the effect of pressure on the Fermi surface and superconducting transition temperature of thallium

The authors used a local pseudopotential model, which includes the effect of spin-orbit coupling, to calculate the effect of pressure on cross sectional areas of the Fermi surface of thallium. The calculated results are compared with the experimental values measured using the de Haas- van Alphen effect reported by Anderson et al. The interpretation by Makarov et al of the anomalous pressure variation in the superconducting transition temperature as due to a topology change in the Fermi surface is confirmed. Two topology changes are considered that occur in thallium and show that the minute fourth zone electron pockets (situated along the line Gamma to M) reported by Capocci et al, have just the correct Fermi energy to cause a nonlinear variation in Tc as the pressure is varied.