  In this paper we develop a link between the atomic-level modeling of the
glide of 1/2<111> screw dislocations at 0 K and the thermally activated motion
of these dislocations via nucleation of pairs of kinks. For this purpose, we
introduce the concept of a hypothetical Peierls barrier, which reproduces all
the aspects of the dislocation glide at 0 K resulting from the complex response
to non-glide stresses and is expressed in a compact form by the yield criteria
advanced in Part II. To achieve this the barrier is dependent not only on the
crystal symmetry and interatomic bonding but also on the applied stress tensor.
Standard models are then employed to evaluate the activation enthalpy of
kink-pairs formation, which is now also a function of the full applied stress
tensor. The transition states theory links then this mechanism with the
temperature and strain rate dependence of the yield stress.
