... symmetry directions; they possess the symmetry group Oh(m3m). A tensile stress in the x-direction, for example, will strain the lattice in the xy-planeand destroy the three-fold symmetry, thereby ... three-fold symmetry, thereby lifting the degeneracy of the energy minima. However, the four-fold symmetry along the x-direction will be preserved. Thus, the two valleys along the direction of stresswill ... by CRC Press LLCAccording to the deformation potential theory, the strain will shift the energy of all the states in a given bandextremum by the same amount, i.e., the valley moves along the...