H4(+): what do we know about it?

The potential energy surface of H(4)(+) has been analyzed and stationary points and minima of intersections characterized by benchmark multireference configuration interaction calculations with basis sets as large as augmented septuble zeta. No evidence for minima other than those of the well established stable C(2v) configuration has been found. Some of the results obtained previously at a lower level of ab initio theory had to be revised.