Improved binding energies for LiPs, e(+)Be, NaPs and e(+)Mg

The stochastic variational method and its fixed core variant are applied to the calculation of lithium positride (LiPs), positronic beryllium (e(+)Be) , sodium positride (NaPs) and positronic magnesium (e(+)Mg). The revised bi nding energy of Lips was 0.012 341 Hartree, that for e(+)Be was 0.031 47 Ha rtree, that for NaPs was 0.008 419 Hartree and the binding energy for e(+)M g was 0.015 612 Hartree. The binding energies for LiPs and e(+)Be are expec ted to be within 2% of the variational limit. The uncertainties in the NaPs and e(+)Mg binding energies are larger and these are expected to be within 10-15% of the variational limit.