The role of configuration space dimension in helium

Quantum states associated with two characteristic configurations of the three body Coulomb problem are identified in ab initio quantum calculations on helium confined to a one, two and three dimensional configuration space. We compare the autoionization rates of these states and find that the two dimensional restriction leads to results that are in quantitative agreement with those of the real physical system, whilst confinement of the nucleus and the two electrons to one single dimension can lead to a dramatic underestimation of the actual decay rates (by orders of magnitude). (orig.)