Deuteron ($A=2,J=1,I=0$)

The bound atomic nucleus containing one proton and one neutron. Its ground-state spin is one and its isospin is zero. The appropriately quantized toroidal two-Skyrmion models these quantum numbers.

The deuteron has a dominant ${}^3{S}_1$ component and a smaller ${}^3{D}_1$ component coupled by the nuclear tensor force. The electric quadrupole moment rules out a purely isotropic S wave spatial state. A D-state probability depends on the chosen nuclear Hamiltonian and current approximation; it is not an independently model-free observable.