This book discusses group theory investigations of zincblende and wurtzite semiconductors under
symmetry-breaking conditions. The text presents the group theory elements required to develop a
multitude of symmetry-breaking problems giving scientists a fast track to bypass the need for
recalculating electronic states. The text is not only a valuable resource for speeding up
calculations but also illustrates the construction of effective Hamiltonians for a chosen set
of electronic states in crystalline semiconductors.Since Hamiltonians have to be invariant
under the transformations of the point group the crystal symmetry determines the multiplet
structure of these states in the presence of spin-orbit crystal-field or exchange
interactions. Symmetry-breaking leads to additional coupling of the states resulting in shifts
and or splittings of the multiplets. Such interactions may be intrinsic as in the case of the
quasi-particle dispersion or extrinsic induced bymagnetic electric or strain fields. Using
a power expansion of the perturbations these interaction terms can be determined in their
parameterized form in a unique way. The hierarchic structure of this invariant development
allows to estimate the importance of particular symmetry-breaking effects in the Hamiltonian. A
number of selected experimental curves are included to illustrate the symmetry-based
discussions which are especially important in optical spectroscopy.This text is written for
graduate students and researchers who want to understand and simulate experimental findings
reflecting the fine structure of electronic or excitonic states in crystalline semiconductors.
