Work function and surface energy of optimized lithium slabs

The electronic work function and surface energy are calculated for the principal surfaces of body-centered-cubic Li. Results for three-layer Li slabs with the bulk lattice parameter show that the work function increases in the order (100), (111), and (110) in the surface orientation, which differs from the prediction of the jellium model with pseudopotential corrections. The results of the structural optimization show that the dependence of the work function and surface energy on the surface orientation almost vanishes for very thin slabs. Energetically the most stable one of these three investigated slabs is the (111) slab. In all three cases, the central layer seems to have a tendency toward bulklike behavior, which significantly affects the relaxation of the slab.