title: Efficient Calculations with Multisite Local Orbitals in a Large-Scale DFT Code CONQUEST.
abstract: Multisite local orbitals, which are formed from linear combinations of pseudoatomic orbitals from a target atom and its neighbor atoms, have been introduced in the large-scale density functional theory calculation code CONQUEST. Multisite local orbitals correspond to local molecular orbitals so that the number of required local orbitals can be minimal. The multisite support functions are determined by using the localized filter diagonalization (LFD) method [ Phys. Rev. B 2009 , 80 , 205104 ]. Two new methods, the double cutoff method and the smoothing method, are introduced to the LFD method to improve efficiency and stability. The Hamiltonian and overlap matrices with multisite local orbitals are constructed by efficient sparse-matrix multiplications in CONQUEST. The investigation of the calculated energetic and geometrical properties and band structures of bulk Si, Al, and DNA systems demonstrate the accuracy and the computational efficiency of the present method. The representability of both occupied and unoccupied band structures with the present method has been also confirmed.
authors.affiliation: International Center for Young Scientists (ICYS), National Institute for Materials Science (NIMS) , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.|Computational Materials Science Unit (CMSU), National Institute for Materials Science (NIMS) , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Nakata
authors.affiliation: Department of Physics & Astronomy, University College London , Gower Street, London WC1E 6BT, U.K.|WPI-MANA, National Institute for Materials Science (NIMS) , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.|London Centre for Nanotechnology, University College London , 17-19 Gordon Street, London WC1H 0AH, U.K.
authors.forename: David R
authors.initials: DR
authors.lastname: Bowler
authors.affiliation: Computational Materials Science Unit (CMSU), National Institute for Materials Science (NIMS) , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.|Department of Physics & Astronomy, University College London , Gower Street, London WC1E 6BT, U.K.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Miyazaki