I'm essentially a math student working on algorithms for a chemistry problem involving rotational spectra, and I keep coming across references to Wang transformations but have been unable to track down what the Wang basis is. You can assume I have the analysis background to understand what a basis of a function space is.
It was developed by S. C. Wang, as referenced by King, Hainer and Cross in Journal of Chemical Physics 11, pg 27 and S. C. Wang in Physical Review 34, p.243, 1929 (where I think it's defined) It doesn't show up in any of the math texts I have (up to Rudin's Functional Analysis) or any of the classical mech or quantum texts I have (which are more the undergrad level).
Best I can make out is that it transforms the wave functions from a symmetric rotor basis to something that is characterized by representations of the Klien Four group. It's used because it eases the computation of the eigenvalues of the Hamiltonians, used to compute transitions of the rotational spectrum.
So, in short, what is the Wang basis?