  We consider the standing wave solutions of the three dimensional semilinear
Schrodinger equation with competing potential functions $V$ and $K$ and under
the action of an external electromagnetic vector field $A$. We establish some
necessary conditions for a sequence of such solutions to concentrate, in two
different senses, around a given point. In the particular but important case of
nonlinearities of power type, we prove that the spikes locate at the critical
points of a smooth ground energy map independent of $A$.
