Dependence of work function on the order-disorder phase transition in chemisorbed layers

The effect of the order-disorder phase transition in chemisorbed layers on the change of work function is studied with the tight-binding approximation. Charge transfers are calculated using the first terms in a continued-fraction series for the electronic Green's function. A sizable decrease in the work function with respect to the disordered phase at a given coverage is found. This leads to a minimum in the work-function versus coverage curve not found for the random nonequilibrium distribution.