Weak Dispersive estimates for Schr\"odinger equations with long range   potentials
  We prove some local smoothing estimates for the Schr\"{o}dinger initial value problem with data in $L^2(\mathbb{R}^d)$, $d \geq 2$ and a general class of potentials. In the repulsive setting we have to assume just a power like decay $(1+|x|)^{-\gamma}$ for some $\gamma>0$. Also attractive perturbations are considered. The estimates hold for all time and as a consequence a weak dispersion of the solution is obtained. The proofs are based on similar estimates for the corresponding stationary Helmholtz equation and Kato H-smooth theory. 
J. A. Bercelo, A. Ruiz, L. Vega, M. C. Vilela