  The oxidation of {\alpha}-Ti(0001) surface was studied using density
functional theory. In order to enhance the oxidation resistance, we substituted
Ti atoms with Si atoms in Ti(0001) surface. We observe that Si prefers to
segregate at the surface layer of Ti(0001) compared to other sub-surface
layers. The Si solubility on the Ti(0001) surface was estimated to be around 75
at.%. While Si segregation was found to reduce the binding between the oxygen
atom and the Ti(0001) surface, the barrier for oxygen to diffuse into the slab
increases. The dissociation of the oxygen molecule on the clean and Si
segregated surfaces of Ti was found to be barrier-less. Overall, the Si
segregation on the Ti(0001) surface was found to hinder the dissolution of
oxygen in Ti.
