The existence of stable ground states for the exotic species MgeC and NaPs was demonstrated by using a modified version of the stochastic variational method to solve the Schr¨odinger equation for a model potential. The model potential consisted of the direct interaction between the positron and electrons with a Hartree–Fock wavefunction for the 10- electron core. The exchange potential between the valence electrons and the core electrons is approximated by using a local potential. It is found that MgeC is stable against decay into eC C Mg with a binding energy of 0:012 790 Hartree and NaPs is stable with a binding energy of 0:005 892 Hartree.