ThestudyofsurfacestructureandGasegregationinMnSb(0001)surface usingfirstprinciples Surface relaxation and surface formation energy were calculated for different MnSb(0001)-(1×1) terminated surface using first-principles density functional theory. After geometry optimization, we find that the Sb-terminated surface experiences smaller relaxations and is much more stable under both Mn-rich and Sb-rich conditions. In addition, Ga surface segregation through the MnSb film from the GaAs substrate is confirmed from our experiments. Therefore, models were designed where Ga is incorporated into the MnSb structure. Occupation of Mn substitutional sites just below the surface is found to be favourable. A (2 × 2) surface reconstruction of n-MnSb was experimentally observed using reflection high energy electron diffraction. Here, CASTEP and CLEED are employed to understand the formation of the (2×2) surface reconstruction.