  We propose a theoretical framework to predict the deformation mechanism of
the {\gamma}-TiAl single crystal without lattice defects by combining the
generalized stacking fault energy and the Schmid factor. Our theory is
validated against an excellent testbed, the single crystal nanowire, by
correctly predicting four major deformation mechanisms, namely, ordinary slip,
super slip, twinning, and mixed slip/fracture observed during the tensile and
compressive tests along 10 different orientations using molecular dynamics
simulations. Interestingly, although lattice defects are not taken into
account, the theoretical predictions match well with existing experiments on
bulk specimen with only a few exceptions; the exceptions are discussed based on
the size-dependent deformation mechanism in the presence of preexisting
dislocation sources. We expect that the method in this paper can be generalized
to study various ductile intermetallic crystals where conventional Schmid law
does not hold well.
