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For pt. I see ibid., vol.2, 1055-61 (1972). The use of the k dependent potential is described. The band structure of Ca and its Fermi surface are computed with this potential and it is shown that the results are a marked improvement on those given by conventional potentials. The energy eigenvalues are computed for symmetry points for Al and it is shown that fair agreement is obtained with results obtained from a pseudopotential. It should be stressed that the potential used is entirely a priori, with no adjustable parameter.

The conduction bands for Ca have been computed with a Slater-type potential and it is found that for less than 20% or more than 75% of the exchange term there is no overlap between the first and second band. The conduction and core bands, density of states, Fermi energy and Fermi surface are computed for an optimum value of the exchange. It is found that the Fermi surface is connected and agreement with all the known results of the de Haas-van Alphen effect is obtained. Although this is in apparent disagreement with the results of Vasvari et al. who obtain an unconnected Fermi surface, their Fermi level was wrongly located and when the error is corrected a connected surface should almost certainly be obtained. The effect of pressure on the Fermi surface and conductivity of Ca is discussed.