Abstract
We have studied the structural, electronic and half metallic ferromagnetic properties of Ga1-xMnxAs compounds at dopant concentrations x=0.25, 0.125 and 0.0625. First principle calculations based on density functional theories as implemented in SIESTA code using LDA as exchange correlation (XC) potential have been used to study the properties of these compounds. The calculated results predict that Mn doped GaAs diluted magnetic semiconductors exhibit half metallic properties at different concentrations.