  First-principles full potential calculations based on Zeroth Order Regular
Approximation (ZORA) relativistic Hamiltonian and Kohn-Sham form of Density
Functional Theory (KS DFT) in local spin density approximation (LSDA) are
reported for group IIIA-VA (InAs, GaAs, InP) semiconductors. The effects of
relativity are elucidated by performing fully relativistic, scalar
relativistic, and nonrelativistic calculations. Structural and electronic band
structure parameters are determined including split-off energies, band gaps,
and deformation potentials. The nature of chemical bonding at the equilibrium
and under hydrostatic strain is investigated using projected (PDOS) and overlap
population weighted density of states (OPWDOS). ZORA results are compared with
Augmented Plane Wave plus Local Orbitals method (APW+lo), and experiment.
Viability and robustness of the ZORA relativistic Hamiltonian for investigation
of electronic and structural properties of semiconductors is established.
