  We report an ab initio evaluation of the surface energy of a simple metal,
performed via a coupling-constant integration over the dynamical
density-response function. The rapid rate of change of the electron density at
the surface is treated exactly. Long-range correlations are treated
self-consistently in the random-phase approximation; short range correlations
are included in time-dependent local density-functional theory. Our results
provide a numerical measure of the error introduced by the usual local-density
approximation; this error is found to be small.
