The problem of metal-dielectric (MD) phase transitions has recently been attracting an enormous amount of attention from numerous investigators, both in our country and abroad. This interest arises out of the importance of the problem both in its practical aspect, i.e., for the possibility of developing various technical instruments and devices based on metal-dielectric transitions, and for its fundamental scientific implications. Study of metal-dielectric phase transitions improves our understanding and recognition of the effects of various physical phenomena on the electronic properties of matter.