Travelling waves for the Gross-Pitaevskii equation I
In this paper we establish a variant and generalized weak linking theorem, which contains more delicate result and insures the existence of bounded Palais–Smale sequences of a strongly indefinite functional. The abstract result will be used to study the semilinear Schrödinger equation , where are periodic in for and 0 is in a gap of the spectrum of ; . If for an appropriate constant , we show that this equation has a nontrivial solution.
In this paper we establish a variant and generalized weak linking theorem, which contains more delicate result and insures the existence of bounded Palais–Smale sequences of a strongly indefinite functional. The abstract result will be used to study the semilinear Schrödinger equation , where N ≥ 4; V,K,g are periodic in xj for 1 ≤ j ≤ N and 0 is in a gap of the spectrum of -Δ + V; K>0. If for an appropriate constant c, we show that this equation has a nontrivial solution.