In this paper, first-principles calculations provide structural characterization of three low-index Mg surfaces—Mg(0001), $\mathrm{Mg}(10\overline{1}0$), and $\mathrm{Mg}(11\overline{2}0$)—and their respective surface core-level shifts (SCLSs). Inspired by the close similarities between Be and Mg surfaces, we also explore the reconstruction of $\mathrm{Mg}(11\overline{2}0$). Through the calculation of surface energies and the use of the angular-component decomposed density of states, we show that reconstructions are likely to occur at the $\mathrm{Mg}(11\overline{2}0$) surface, similarly to what was found earlier for $\mathrm{Be}(11\overline{2}0$). Indeed, the surface energy of some of the explored reconstructions is slightly lower than that of the unreconstructed surface. In addition, because of lattice symmetry, the morphology of the unreconstructed surface ($11\overline{2}0$) results in a steplike zig-zag chain packing, with topmost chains supporting a resonant, quasi-one-dimensional (1D), partially filled electronic state. As the presence of partially filled quasi-1D bands is a necessary condition for Peierls-like dimerization, we verify that the undimerized surface chain remains stable with respect to it. Some of the reconstructions, namely, the $2\times 1$ and $3\times 1$ added row reconstructions, induce a stronger relaxation of the topmost chains, increasing the coupling with lower layers and thus significantly damping the quasi-1D character of this state. The original approach followed offers a common and general framework to identify quasi-1D bands—even in the case of resonant electronic surface states—and to meaningfully compare calculated and measured SCLSs even in the presence of multicomponent peak contributions.

• Received 15 December 2017
• Revised 22 May 2019

DOI:https://doi.org/10.1103/PhysRevB.100.075405