  Surface and curvature properties of asymmetric nuclear matter are studied
beyond the proton drip. Using the semiclassical extended Thomas-Fermi method,
the calculations are performed in the non-relativistic and relativistic meson
field theories (Skyrme forces and non linear sigma-omega parametrizations).
First we discuss the bulk equilibrium between the nuclear and drip phases. Next
we analyze the asymmetric surface as a function of the bulk neutron excess. We
examine local quantities related to the density profiles and, for two
definitions of the bulk reference energy, the surface and curvature energy
coefficients. The calculation of the curvature energy is carefully treated. The
sensitivity of the nuclear surface to the relativistic effects is investigated.
Mass formulae useful for arbitray neutron excess are discussed, and their limit
at small asymmetries is compared with the liquid droplet model mass formula.
