Complex scaling in the cluster model: Resonances in 8Be

To find the positions and widths of resonances, a complex scaling of the intercluster relative coordinate is introduced into the resonating-group model. In the generator-coordinate technique used to solve the resonating-group equation, the complex scaling requires minor changes in the formulas and code. The finding of the resonances does not need any preliminary guess or explicit reference to any asymptotic prescription. The procedure is applied to the resonances in the relative motion of two ground-state α clusters in ⁸Be, but is appropriate for any systems consisting of two clusters.