Formula_17971

\[\delta=\frac{T^{2}}{\hbar^{2}}\left[\left\langle\Psi(0)\left|\hat{\bar{H}}^{2}\right| \Psi(0)\right\rangle-(\langle\Psi(0)|\hat{\vec{H}}| \Psi(0)\rangle)^{2}\right]\]