Resonances of the helium atom in a strong magnetic field

We present an investigation on the resonances of a doubly excited helium atom in a strong magnetic field covering the regime B = 0-100 a.u. A full-interaction approach which is based on an anisotropic Gaussian basis set of one-particle functions being nonlinearly optimized for each field strength is employed. Accurate results for a total of 17 resonances below the threshold of consisting of He+ in the N=2 state are reported in this work. This includes states with total magnetic quantum numbers M=0,-1,-2 and even z-parity. The corresponding binding energies are compared to approximate energies of two-particle configurations consisting of two hydrogen-like electrons in the strong field regime, thereby providing an understanding of the behavior of the energies of the resonances with varying field strength.