The alpha - cluster ground state of O

It is shown that there is an α-cluster configuration which is more bound than the optimum regular tetrahedron which is usually assumed to correspond to the ground state of ¹⁸O. There is no sharp minimum in the energy of the ground state of ¹⁶O in the α-cluster model suggesting that the ground state must be a mixture of α-clusters, or that it is important to treat the cluster co-ordinates as dynamical variables.