Elongation method: Towards linear scaling for electronic structure of random polymers and other quasilinear materials

Abstract

We present the linear scaling elongation method for Hartree-Fock and Kohn-Sham electronic structure calculations of either periodic or aperiodic quasi-one-dimensional systems. Linear scaling is achieved through two key computational features: (1) regional localization of molecular orbitals; and (2) a two-electron integral cutoff technique combined with quantum fast multipole evaluation of non-negligible long-range integrals. The accuracy and timing of the method is demonstrated for several systems of interest such as polyglycine and BN nanotubes. Future developments of both a technical and methodological nature are noted including the extension to higher dimensionality as well as higher level wave function treatments.