Gradient blow-up of solutions to the Cauchy problem for the Schrödinger equation

A class of nonlinear Schrödinger operators with singular coefficients is studied. For this class, necessary and sufficient conditions are established for the existence of initial data such that the corresponding solution to the Cauchy problem blows up in finite time. A regularization procedure for the Cauchy problem is proposed, and the limit behavior of the sequence of solutions to the regularized problems is analyzed.