COMPUTATION OF RESONANCES BY 2 METHODS INVOLVING THE USE OF COMPLEX COORDINATES

We have studied two different systems producing resonances, a highly excited multielectron Coulombic negative ion (the He- 2s2p 4P state) and a hydrogen atom in a magnetic field, via the complex-coordinate rotation (CCR) and the state-specific complex-eigenvalue Schrodinger equation (CESE) approaches. For the He- 2s2p2 4P resonance, a series of large CCR calculations, up to 353 basis functions with explicit r(ij) dependence, were carried out to serve as benchmarks. For the magnetic-field problem, the CCR results were taken from the literature. Comparison shows that the state-specific CESE theory allows the physics of the problem to be incorporated systematically while keeping the overall size of the computation tractable regardless of the number of electrons.