Abstract
In a recent article on Al42−, (1) we showed that this species, as an isolated system in the gas phase, has a very short lifetime with respect to electron autodetachment. As for all electronically short-lived systems, standard calculations employing standard basis sets are then highly problematic: Owing to essentially arbitrary mixing with continuum solutions, computations yield arbitrary results for almost all properties. This should not be confused with the normal basis set dependence of all computed properties of electronically stable systems that is orders of magnitude milder.