Sum rules are derived for expressions of the form $\Sigma k^{}{{\omega }_{\mathrm{kn}}}^a{\left|A_{\mathrm{kn}}\right|}^2$; $\mathrm{}\left|a\right|=0, 1, \cdots$. Application of the sum rules are given for various forms of $A$.

• Received 28 December 1966

DOI:https://doi.org/10.1103/PhysRev.157.1220