Calculation of the ground states of H- ion and He atom in magnetic field with a modified configuration interaction method

The modified configuration interaction method is extended to double electro nic systems in magnetic fields. Eigenvalues and binding energies of ground state of H- ion and He atom in uniform magnetic fields are calculated. In a range running from low to intermediate magnetic fields, the best results w ith relative errors of 1.0x10(-5) and 1.4x10(-6) for H- and He, respectivel y are obtained. The accuracy of our results are almost 2 orders of magnitud e better than those obtained by the other methods.