Membranes have a harmonic series in two axes - kind of. They have complex (not that kind of complex, although it also is, in a way) modes on a constrained surfa

Membranes have a harmonic series in two axes - kind of. They have complex (not that kind of complex, although it also is, in a way) modes on a constrained surface which are calculated with Bessel functions. In three dimensions you get atomic orbitals.