${\displaystyle \left|{\frac {X_{m}}{x_{st}}}\right\vert ={\sqrt {\frac {(\alpha ^{2}-\beta ^{2})^{2}+(2\zeta _{a}\alpha \beta )^{2}}{\left[(\alpha ^{2}-\beta ^{2})(1-\beta ^{2})-\mu \alpha ^{2}\beta ^{2}\right]^{2}+(2\zeta _{a}\alpha \beta )^{2}(1-\beta ^{2}-\mu \beta ^{2})^{2}}}}}$

${\displaystyle \alpha _{opt}={\frac {1}{1+\mu }}}$

${\displaystyle \zeta _{a\ opt}={\sqrt {\frac {3\mu }{8(1+\mu )}}}}$