Density functional theory study of flat and stepped NaCl(001)

The properties of bulk NaCl, NaCl (001), and stepped NaCl (001) surfaces have been examined with density functional theory within the plane-wave pseudopotential approach. Aiming to remedy the lack of quantitative energetic and structural knowledge of such surfaces, we employ the local-density approximation and generalized gradient approximation of Perdew-Burke-Ernzerhof (PBE) exchange-correlation functionals as well as the PBE Wu-Cohen functional Phys. Rev. B. 73, 235116 (2006) to determine the surface energy and surface structure of NaCl (001). A range of 9--150. 3em{0ex}meV∕^2 is obtained for the surface energy of NaCl (001), and the surface is predicted to undergo only small relaxations of the top layer atoms, consistent with low-energy electron diffraction I-V analyses. The isolated step formation energy of monoatomic (100) -like steps on NaCl (001) is estimated to be about 40--600. 3em{0ex}meV∕ and the interaction energy between adjacent steps is weak. Thermodynamics has been employed to determine the relative stabilities of stoichiometric (100) -like and nonstoichiometric (111) -like steps on NaCl (001), revealing that (100) -like steps are significantly more stable than (111) -like steps at all accessible values of the chlorine chemical potential.