DEPENDENCE OF THE CRITICAL TEMPERATURE OF SUPERCONDUCTORS ON THE PHONON SPECTRUM.

The temperature equations of Eliashberg are solved for a strong-bonded superconductor by approximating the eigen-energy part SIGMA //2( omega ) with the sample function of Morel and Anderson, and a formula is found for the critical temperature T//c (without allowing for electron decay effects). Using a phonon spectrum of two Einsteinian frequencies T//c is investigated as a function of the position of the low-frequency peak of the function alpha **2( mu ) F( mu ) and it is shown that the appearance of such a peak in a sufficiently low-frequency range begins to weaken the superconductivity. Besides this, it is shown that both by using the sample function of Morel and Anderson for SIGMA //2( omega ) instead of a stepped sample function, and improvement of the model approximating the renormalizing factor ZETA ( omega ) for the strong-bond case, result in lower calculated values of T//c.