THRESHOLD 'COLLAPSE' OF FLUCTUATION LEVELS AND ABRUPT TERMINATION OF DENSITY-OF-STATES TAILS.

A theoretical study is conducted of the influence of the interaction of electrons with acoustic phonons on the distribution of the density of states rho (E) varies directly as exp left bracket minus S(E) right bracket in fluctuation tails. A parabolic dependence S(E) equals A vertical E vertical ** one-half applies to a rigid lattice, but in the case of a deformable lattice it is valid only at relatively low values of vertical E vertical . An increase in vertical E vertical causes S(E) to rise monotonically deviating increasingly from the parabolic dependence and obeying the inequality S(E) less than A vertical E vertical ** one-half . At a critical energy E equals E//t the curve rho (E) terminates abruptly dropping to rho (E) equals 0. The termination point E//t of a density-of-states tail owes its existence to self-localization of electrons, which causes a 'collapse' of the fluctuation levels.