Formula_26373

\[\left.\begin{array}{l}\frac{\partial A_{v}}{\partial a_{\mu}}=\frac{\left[A_{v}, A_{\mu}\right]}{a_{v}-a_{\mu}}, \quad \mu \neq v, \\\frac{\partial A_{v}}{\partial a_{\mu}}=-\sum_{\mu \neq v} \frac{\left[A_{v}, A_{\mu}\right]}{a_{v}-a_{\mu}} .\end{array}\right\}\]