ANOMALY IN THE ANISOTROPY OF THE ALUMINUM WORK FUNCTION

Ab initio calculations combined with a recently developed macroscopic- averaging technique have been used to examine the anisotropy of the al uminum work function. Our results indicate that the Al(111) work funct ion is substantially lower than the Al(100) work function, and slightl y below the Al(110) work function. This is in contrast to other fee me tals, for which a (110) --> (100) --> (111) increasing trend is observ ed experimentally and predicted by Smoluchowski's rule. We show that t he aluminum work-function anomaly, which is in agreement with experime nt, is due to the increased p-atomic-like character of the density of states at the Fermi energy, as compared to most other fee metals. [S01 63-1829(98)50436-5].