New Insights into the Structure of the C-Terminated β-Mo2C (001) Surface from First-Principles Calculations

摘要

Periodic density functional theory (DFT) calculations have been used to study the stability of five different C-terminations of the Mo2C(001) surface in the most stable orfhorhombic (β) phase of this important material. The different terminations all have similar values of the work function or atomic charges, indicating a similar electronic structure, although the analysis of the cleavage energy suggests that the non polar C-terminated surfaces will be the extended terminations seen under thermodynamic equilibrium. Nevertheless, the calculated DFT cleavage energy values together with statistical arguments indicate that different C-terminated motifs are likely to coexist even at temperatures just below annealing conditions.