| Abstract: | Electronically metastable states can efficiently be investigted using ??2 techniques, such as the complex absorbing potential (CAP) or the stabilization method; but, the study of autodetaching systems is nonetheless far more expensive than the investigation of comparable bound states. The costly step of the ??2 methods for resonances involves the repeated diagonalization of a parameterized Hamilton operator, and in this communication we investigate representations of the needed operators in very small basis set consisting of a few eigenstates of the physical Hamiltonian. It is shown that CAP calculations can indeed be performed using a very small eigenstate basis set, whereas basis sets of comparable size are unsuitable for stabilization calculations. Our results allow us to study the frequently employed energy selection procedure in the context of Siegert energies. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 218–226, 2001 |
