[en] The ab initio pseudofunction method has been used to compute electronic properties of superconductors in good agreement with experiment. La₂CuO₄ and CuO are computed to be antiferromagnetic and semiconducting in agreement with experiment. The 0.4-eV peak in the optical conductivity spectrum has been shown to be an interband transition for YBa₂Cu₃O₇. The bands for Bi₂Sr₂CaCu₂O₈ as well as YBa₂Cu₃O₇ agree well with angle-resolved photoemission near E_f. The shake-up peaks near 9 and 12 eV observed in photoemission can be understood in terms of two-electron processes envolving the local densities of states of Cu and O. A mechanism for superconductivity based on these electronic properties will be advanced. All calculations use local density potentials with no parameters