Sodium and sulphur bilayers on a nickel (001) surface

Abstract
Sodium and sulphur on an (001) nickel surface are investigated in the c(2*2)S-c(2*2)Na, c(2*2)S-p(2*2)Na, and p(2*2)S-p(2*2)Na configurations. Sulphur always sits in hollows 1.3 AA from the nickel surface. Sodium always lies above hollows in the nickel substrate 2.5 AA from the substrate, but prefers to maximize the number of sulphur nearest neighbours.