Gradient Estimates via Rearrangements for Solutions of Some   Schr\"odinger Equations
  In this article, by applying the well known method for dealing with $p$-Laplace type elliptic boundary value problems, the authors establish a sharp estimate for the decreasing rearrangement of the gradient of solutions to the Dirichlet and the Neumann boundary value problems of a class of Schr\"odinger equations, under the weak regularity assumption on the boundary of domains. As applications, gradient estimates of these solutions in Lebesgue spaces and Lorentz spaces are obtained. 
Sibei Yang, Der-Chen Chang, Dachun Yang and Zunwei Fu
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