Variational study of H⁻and He in strong magnetic fields

Two-electron systems in strong magnetic fields (>or=1 MT) are studied with a simple Slater-determinant basis which allows different types of configuration mixing. Variational energies of the lowest singlet and triplet bound states are obtained for values 0 to -2 of the magnetic quantum number. They improve previous results and show the importance of correlations. The order of the -2 T + and -2 S + states is found to be different in the H - and He spectra.