Structure of 3He

Using electron scattering data, the diffraction pattern off $$^{3}$$ 3 He shows it to be an equilateral triangle possessing dihedral D$$_{3}$$ 3 point group symmetry (PGS). Previous work showed that $$^{4}$$ 4 He is a 3-base pyramid with C$$_{3v}$$ 3 v PGS. $$^{6}$$ 6 Li is predicted to have C$$_{2v}$$ 2 v PGS. As nuclear $$A \rightarrow $$ A → large, atomic nuclei enter into the ‘protein folding problem’ with many possible groundstate PGS competing for lowest energy.