Theory of field evaporation of the surface layer in jellium and other metals

An intense, positive electric field applied normal to a metal surface can displace or even strip away the surface layer of atoms. These effects are studied for a jellium model (r_s=4.20 a.u., surface layer thickness d=5.65 a.u.) via fully self-consistent calculations within the local-density approximation for exchange and correlation. From plots of surface energy versus displacement for several fields of interest, the critical field F_c required to evaporate the rigid surface layer is found (1.8 V/Å) and compared with the prediction (1.7 V/Å) of a simple semiempirical formula based upon universal binding-energy curves. The calculations also reveal information about electronic-charge redistribution, electronic resonances which develop with increasing separation of the surface layer from the bulk, and various components of the surface-layer–bulk binding force. The jellium surface is compared with the real-metal surface Na(110) and with Al(111), which was investigated in earlier semi-self-consistent work.