Resonances of the hydrogen atom in strong parallel magnetic and electric fields

The behavior of the rsonances of a hydrogen atom in parallel magnetic and electric fields is obtained with a complex scaling plus B-spline method. The resonant parameters E and ${\mathrm{\ensuremath{\Gamma}}}_{0}$ in an electric field alone are consistent with those obtained by other methods. In a fixed electric field F the widths \ensuremath{\Gamma} of both the ground and excited resonances decrease with an increase of the magnetic field B, and the relative variation (\ensuremath{\Gamma}-${\mathrm{\ensuremath{\Gamma}}}_{0}$)/${\mathrm{\ensuremath{\Gamma}}}_{0}$ is directly proportional to the ratio of the magnetic-field strength to the electric-field strength. The positions of the resonances, however, are pushed higher by an increasing of magnetic field. The pushing effect is insensitive to the electric-field strength and depends almost entirely on the magnetic-field strength.