Collapse in the n‐Dimensional Nonlinear Schrödinger Equation—A Parallel with Sundman's

Collapse of solutions of the n ‐dimensional nonlinear Schrödinger equation are studied using the integrals of the motion and an equation corresponding to the Lagrange‐Jacobi virial equation of classical mechanics. There are strong parallels with collapse in the classical N ‐body problem and in particular with the results of K. F. Sundman. Collapse occurs when the amplitude of the solution becomes singular as the initial data collapse to the center of mass in finite time. In some cases the singularity is inevitable (for negative energy), but in others only a necessary condition for collapse can be derived, involving the angular momentum.