Magnetic-field effects on the ##IMG## [http://ej.iop.org/images/0953-4075/31/6/007/img3.gif] Feshbach resonances below the H ( N = 2) threshold and the ##IMG## [http://ej.iop.org/images/0953-4075/31/6/007/img3.gif] shape resonance of ##IMG## [http://ej.iop.org/images/0953-4075/31/6/007/img5.gif] lying above the H ( N = 3) threshold are investigated theoretically using a method of complex-coordinate rotation. Products of Slater-type orbitals (STOs) are used to represent the two-electron wavefunctions, with ##IMG## [http://ej.iop.org/images/0953-4075/31/6/007/img6.gif] being employed for individual electrons. Block matrices with up to ##IMG## [http://ej.iop.org/images/0953-4075/31/6/007/img7.gif] (K-states) are used. Convergence behaviour for the resonance parameters (resonance energy and width) is examined by using different values of ##IMG## [http://ej.iop.org/images/0953-4075/31/6/007/img8.gif] . When the external magnetic field is turned on, we examine the field effects on the resonance energies and the autoionization widths. A physical interpretation of our results is given.
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