An anisotropic harmonic oscillator in three dimensions is given by the potential:
$$V(X,Y,Z)=\frac{1}{2}m\omega^2\bigg[\bigg(1+\frac{2\lambda}{3}\bigg)(X^2+Y^2)+\bigg(1-\frac{4\lambda}{3}Z^2\bigg)\bigg].$$
The energy eigenvalues of the stationary states are:
$$E_{n_x,n_y,n_z}=(n_x+n_y+1)\hbar\omega\sqrt{1+\frac{2\lambda}{3}}+(n_z+\frac{1}{2})\hbar\omega\sqrt{1-\frac{4\lambda}{3}}.$$
It is obvious that the potential has a defined parity, because under a change $\boldsymbol{r}\rightarrow-\boldsymbol{r}$ it remains the same function. How does this defined parity affect the eigenvalues of $H$?
Because there is no explicit dependence on the coordinates in $E_{n_x,n_y,n_z}$, it seems like there is nothing to say about the parity of the eigenvalues. Still, the problem I am posting is from Cohen-Tannoudji's book of quantum mechanics, and he asks to discuss the parity and the degree of degeneracy of the ground State for this harmonic oscillator.