CI-SD/[3s2p] and MCSCF/[3s2p] calculations were performed in order to obtain
detailed information on the potential energy surface of H4+. Jahn-Teller
distortions from the square geometry of H4+ are studied and it is shown that
the optimal distorted geometries are slightly different from those obtained by
following Jahn-Teller active modes. The results are compared with previous
studies and the reliability of the single reference CI-SD approach to this
problem is discussed.