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\begin{equation}
\label{eq:schroedinger}
\mathrm{i}\cdot\hbar\cdot\frac{\partial}{\partial t}\psi(\mathbf{r},t) \;=\; - \frac{\hbar^2}{2m}\cdot\nabla^2\psi(\mathbf{r},t) + V(\mathbf{r},t)\cdot\psi(\mathbf{r},t)
\end{equation}

\eqref{eq:schroedinger} is an equation.
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