Hartree-Fock mesh calculations of the energy levels of the helium atom in magnetic fields

The mesh method of solving the Hartree-Fock equations for atoms in magnetic fields of arbitrary strength is presented. The method is applied for the ground and a series of excited states of the He atom. The energy levels of the ion He+ in the states with n=1 and 2 are also calculated for the same strengths of the magnetic field as for the He atom. The use of the mesh method results in reaching the Hartree-Fock energy limit for fields from weak to strong, including the intermediate field region.