Corrected effective-medium method. IV. Bulk cohesive and surface energies of second- and third-row metals and multilayer relaxation of Al, Fe, and Ni

Abstract

We provide a detailed analysis and discussion of the recently developed corrected effective-medium method (CEM) as applied to calculations of the bulk cohesive energies of the second- and third-row metals. The results demonstrate that a quantitatively accurate description of these quantities requires a new ‘‘covalent’’ embedding function instead of the self-consistent-field local-density ‘‘ionic’’ embedding function of Puska and co-workers. Construction of these covalent embedding functions from diatomic and bulk electron-density binding potentials is detailed. We present the formalism within the CEM method for the calculation of the surface energy of infinitely periodic two-dimensional solid surfaces. Calculations of the surface energies for the perfectly terminated low-Miller-index faces of Na, Mg, Al, K, Ca, Fe, Ni, and Cu are carried out. These results are compared to experimental measurements and very good agreement is found for almost all of these metals. More demanding multilayer surface-relaxation calculations are performed for Al(111), (110), and (100), Ni(110) and (100), and Fe(100). Very good agreement with experimental observations is obtained for these systems with the exception of Al(111) and (100). Detailed analysis of these calculations leads to an explanation of the relaxation process and its driving components.