  A computer simulation of thermofluctuation nucleation of kinks on
dislocations and their dynamics is carried out in the framework of
two-dimensional (2D) Frenkel-Kontorova model. It is shown that at relatively
low temperatures and applied stresses the kinks can appear as a result of
developing instability of phonon modes localized in the vicinity of the
dislocation. The transition from this mechanism to the ordinary
thermofluctuation kink nucleation with temperature increase can reveal itself
in the peculiarities of yield stress temperature dependence.
