“…Recently, Di Nezza, Palatucci, and Valdinoci [9] gave a survey on the fractional Sobolev spaces, which are more convenient for fractional Laplacian equations. Lee, Kim, Kim, and Scapellato [18] examined the existence of at least two distinct nontrivial solutions to a Schrödinger-type problem involving the nonlocal fractional p-Laplacian with concave-convex nonlinearities. Since then, there have been some works on the existence, multiplicity, and concentration phenomenon of solutions to the nonlinear fractional Schrödinger equation (1.2) and other differential problems driven by Laplace-type operators; see [1, 2, 7, 10-13, 15, 19-21, 25, 28-32].…”