  We investigate the $L^2$-supercritical and $\dot{H}^1$-subcritical nonlinear
Schr\"{o}dinger equation in $H^1$. In \cite{G1} and \cite{yuan}, the
mass-energy quantity $M(Q)^{\frac{1-s_{c}}{s_{c}}}E(Q)$ has been shown to be a
threshold for the dynamical behavior of solutions of the equation. In the
present paper, we study the dynamics at the critical level
$M(u)^{\frac{1-s_{c}}{s_{c}}}E(u)=M(Q)^{\frac{1-s_{c}}{s_{c}}}E(Q)$ and
classify the corresponding solutions using modulation theory, non-trivially
generalize the results obtained in \cite{holmer3} for the 3D cubic
Schr\"{o}dinger equation.

Analysis of PDEs