Defective Si(1 0 0) surfaces have been used with the aim to explore from a theoretical point of view, the effect of the defects in the Ti/Si interface formation when Ti is deposited on a clean Si surface at room temperature. Results indicate that a complex mechanism occurs where the Si surface stability is an important point to take into account to obtain titanium silicides species of different thickness and Si concentration. Even at room temperature, the thickness of the Ti/Si interface depends not only of the Ti diffusion on the Si surface but also of the Si diffusion on the Ti slab deposited on the Si surface. (C) 2015 Elsevier B.V. All rights reserved.