Abstract
The purpose of this paper is to provide higher order Schrödinger equations from a finite expansion approach. These equations converge toward the semirelativistic equation for particles whose norm of velocity vector is below c/√2 and are able to take into account some relativistic effectswith a certain accuracy in a sense that we define. So, it is possible to take into account some relativistic effects by using Schrödinger form equations, even if they cannot be considered as relativistic wave equations.