The spherical harmonic function $\mathrm{Y}_{\ell, \mathrm{m}}(\theta, \phi)$ with appropriate values of $\ell$ and m , is an eigenfunction of $\hat{\mathrm{L}}_{\mathrm{x}}^{2}+\hat{\mathrm{L}}_{\mathrm{y}}^{2}$ operator. The corresponding eigenvalue is