First-principles analysis of the adsorption of aluminum and chromium atoms on the HfC (0 0 1) surface

We have investigated the surface energies and electronic structures of the HfC (0 0 1) (1 × 1) surface. Calculations were also carried out for the adsorption of Al and Cr atoms on the surface. The structural and electronic properties of bulk HfC were also determined. All of these calculations were based on first principles. We have dealt with the exchange and correlation potential for bulk HfC using the Perdew–Wang generalized gradient approximation (GGA-PW91) (1991). Furthermore, the local density approximation (LDA) was used for the adsorption energy calculations of Al and Cr atoms on the HfC (0 0 1) surface. For Al, Cr atoms on the surface, the adsorption energies confirm the preference for adsorption at the on-top C atoms sites. Moreover, compared with Al atoms, Cr atoms are more easily adsorbed on the HfC (0 0 1) surface. The Cr adatom–surface bonds are stronger than the Al adatom–surface bonds. The C–Al bonds are ionic while the C–Cr bonds present the covalent and metallic characteristics in nature.