H. Chihara, GLOBAL EXISTENCE OF SMALL SOLUTIONS TO SEMILINEAR SCHRODINGER-EQUATIONS, Communications in partial differential equations, 21(1-2), 1996, pp. 63-78
We present global existence theorem for semilinear Schrodinger equatio
ns. In general, Schrodinger-type equations do not admit the classical
energy estimates. To avoid this difficulty, we use S. Doi's method for
Linear Schrodinger-type equations. Combining his method and L(p) - L(
q) estimates, we prove the global existence of solutions with small in
itial data.