4558 n. d. LANG AND W. KOHN 计计计 学计计9宁9宁心后出 点:3 ·::: 2:: R?77777?9?7 身当 N:88A下 到3号8 68888444440988824244-44808888889888888888888 三当写 3号到 a........44.4444 引9;ss 运 器图到5 6乱 注÷沪宁宁宁ss vxc which vanishes exponentially as x-o, where- ployed for vett. However for x>xo, vott was as one would expect that the correct vxc would be taken to have the image form -1/4x, with p have like the classical image potential, i.e computed from(2. 16c)and(2.7). The problem was then solved, for rs=2. 5 and 5, requiring self- consistency of n(x). Fortunately, the densities in To assess the quantitative importance of this fail- these calculations were found to differ from those ure of our approximation, we have carried out the previously obtained by no more than 1. 2% of n for following control calculations. Up to the point xo rs=5, and no more than 0. 3% for rs=2. th where Dett =0, we used the form previously em appears that our use of the form (2. 16b)for vett