Self-consistent charge density and surface electronic states for the (001) face of lithium

The self-consistent electronic energy band structure of a 13-layer (001) film of lithium has been calculated using the method described previously. The crystalline potential is described in terms of a nonlocal pseudopotential, with exchange-correlation effects treated in terms of the local approximation used in the Lang-Kohn jellium studies. The planar averages of both charge density and local part of the potential exhibit Friedel oscillations that are appreciably greater than a superposition of the jellium results on the bulklike envelopes in the inner selvage region; in the outer selvage the planar average of the potential agrees well with the jellium result. The (unoccupied) surface state appearing in the $\overline{X}$ gap of the two-dimensional band structure in our initial communication has descended almost to the bulk band below, and in its place a surface state of complementary planar symmetry has descended into the $\overline{X}$ gap from the bulk band above.