Abstract
The authors derive a variationally accurate expression for the centre of mass z0( sigma ) of the induced charge density at a semi-infinite jellium metal in the presence of a static electric field. This expression generalises the 'displaced-profile change-in-self-consistent-field' (DP Delta SCF) expression of the work function and is shown to give good results with sample two-parameter trial profile for a wide range of electron densities and surface charges.