  We present a case study of the complex temperature dependence of grain
boundary mobility. The same general incoherent twin boundary in different FCC
metals is found to display antithermal, thermal, and mixed mobility during
molecular dynamics synthetic driving force simulations. A recently developed
energy metric known as the generalized interfacial fault energy (GIFE) surface
is used to show that twin boundaries moving in an antithermal manner have a
lower energetic barrier to motion than twin boundaries moving in a thermally
activated manner. Predicting the temperature dependence of grain boundary
motion with GIFE curves stands to accelerate research in grain boundary
science.
