Criteria of accuracy of resonance eigenvalues

Abstract
Various criteria that have been suggested for assessing the accuracy of complex‐coordinate eigenvalues are critically tested in an application to the lowest helium 1S resonance, and found to be relatively ineffective. An alternative criterion is described, based on a generalized stabilization procedure, which seems better able to select the “best” resonance eigenvalue and to guide the construction of variational trial functions.
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