31 May
2011
31 May
'11
9:58 a.m.
On May 31, 2011, at 11:35 AM, Allan Wechsler wrote:
Blah, I answered this just to Henry. I thought of the p-orbitals of electrons, and some vibrational modes of a circular drum, and was sure there were simpler examples of symmetry-breaking but couldn't construct one off the top of my head.
Those are actually not examples of "symmetry-breaking" . The degeneracy (in energy/frequency) is just a manifestation of the symmetry, and indicates the system is especially sensitive to perturbations (that typically "break" the symmetry). Here's an example of true symmetry breaking: the ground state of the lithium trimer (three lithium atoms). If we neglect quantum motion of the nuclei, then the ground state shape is an isosceles triangle. Veit