The quantum phase transitional behavior of an alternative characterization of the spherical to axially deformed shape-phase transition in the interacting boson model is explored. Specifically, the usual SU (3) quadrupole-quadrupole interaction is replaced by an O(6) cubic interaction, and the transitional behavior of the low-lying energy levels, eigenstates, isomer shifts, E2 transition rates, and expectation values of shape variables across the entire transitional region are all examined within this context. A comparison with outcomes of the usual U (5)-SU (3) transitional description shows that the spherical to axially deformed shape-phase transition can also be described within this alternative context, especially near the critical point. However, with the O(6) cubic interaction the transition is considerably smoother than for the U (5)-SU (3) case, but with the nuclear shape less well defined, even in the axially deformed limit. It is also shown that the new scheme seems better than the usual U (5)-SU (3) scheme in describing low-lying spectrum of 152 Sm with the X(5) critical point symmetry.

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