A linear scaling approach for general and accurate pseudopotential Density Functional Theory calculations is presented. It is based on a Finite Difference discretization. Effective O(N) scaling is achieved by confining the orbitals in spherical localization regions. To improve accuracy and flexibility while computing the smallest possible number of orbitals, we propose an algorithm to adapt localization regions during computation. Numerical results for a polyacethylene chain and a magnesium oxide ring are presented
