Detailed first-principles studies on surface energy and work function of hexagonal metals

The surface energies and work functions for ten kinds of Miller-indices surfaces of hexagonal metals, Be, Mg, Tc, Re, Ru, and Os are calculated by means of the density functional theory (DFT) method. The results show that the metals belonging to the same group have a very similar rule in work functions and surface energies. The work functions of (0001), (01 (1) over bar1), and (10 (1) over bar0) surfaces are generally larger than the work functions of (11 (2) over bar1), (11 (2) over bar2), (11 (2) over bar3), and (31 (4) over bar0) surfaces. In contrast to work functions, there is more regularity in the crystallographic orientation dependence of surface energies. However, for the metals belonging to different groups, there are always some differences in the exact order of orientation dependence. It is also shown that the work functions and surface energies of the main group metals decrease as they go from top to the bottom in the same group of periodic table, while for the transition metals, they do not always obey this rule. (C) 2016 Elsevier B.V. All rights reserved.