The expression for the
electron density of states (EDOS) of high temperature superconductors (HTS) has
been derived taking the disorder and anharmonicity effects as a central
problem. This has been dealt with the help of double time thermodynamic Green’s
function theory for electrons via a generalized Hamiltonian which consists of
the contribution due to 1) unperturbed electrons;2) unperturbed
phonons;3) isotopic impurities;4) anharmonicities (no BCS type Hamiltonian
has been taken up in the formulation); and 5) electron-phonon interactions. The renormalization effects and emergence
of pairons appears as a unique feature of the theory and dependence of EDOS on
impurity concentration and temperature has been discussed in details with
special reference to the HTS.
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