  The mean field method is applied for analysis of valence electrons in metals.
It is shown that at low temperatures electrons have two wave-vector
distribution patterns. Isotropic distribution refers to the first pattern.
Anisotropic distribution refers to another pattern, particularly to specific
wave-vector values occurred nearby the Fermi sphere. It is shown that it is the
anisotropy that makes the metal obtain its specific superconductor features.
