We present calculations of the pressure derivatives $A^{\mathrm{-}1}$dA/dP for four Fermi-surface orbits using the ab initio linear muffin-tin orbitals method in the atomic-sphere approximation. Calculations are performed with use of various exchange-correlation (XC) potentials. Our calculations indicate that the ‘‘belly’’ orbits are insensitive to the choice of the XC potential while the ‘‘neck’’ orbit is not. We find that the Xα exchange-correlation potential (with a variable α) gives the best fit to the experimental data.

• Received 1 December 1988

DOI:https://doi.org/10.1103/PhysRevB.39.9806