Abstract
The structural, electronic and optical properties of GaAs1-xBix alloy are investigated using the density functional theory based on the full potential linearized augmented plane wave method as implemented in the Wien2k package. The exchange correlation potential is treated by generalized gradient approximation. We have studied the effect of Bi composition on equilibrium volume, energy band gap, electron and hole effective masses and dielectric function. For the electron and hole effective masses and the dielectric function variations versus bismuth composition, our results represent an attempt to investigate their qualitative trends.