Comparison between plane-wave and linear-scaling localized basis sets for structural calculations of microporous molecular sieves

Abstract

We present a comparison between two computational approaches based on density-functional theory in the generalized gradient approximation with plane waves or localized basis sets, using, respectively, VASP and SIESTA codes. The study is focused on the description of two crystalline microporous aluminophosphates: ${\mathrm{AlPO}}_{4}\ensuremath{-}34$ and ${\mathrm{AlPO}}_{4}\ensuremath{-}18.$ After a necessary optimization of the localized basis set by a simplex method, the results obtained by the two approaches have the same quality but the localized basis set allows a decrease of computer time and memory respectively by a factor of 8 and 2, respectively. An order-N algorithm is then applied. The energy and geometry are again quite similar. This method opens the way to DFT studies on more complex structures.