### Session J19: Frontiers in Electronic Structure Theory I

11:15 AM–2:15 PM, Tuesday, March 6, 2007

Chair: Martin Head-Gordon, University of California, Berkeley

Abstract ID: BAPS.2007.MAR.J19.8

### Abstract: J19.00008 : How localized is local?'' Efficiency vs. accuracy of $O(N)$ domain decomposition in local orbital based all-electron electronic structure theory

1:27 PM–1:39 PM

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#### Authors:

Vile Havu
(Fritz-Haber Institut der MPG)

Volker Blum
(Fritz-Haber Institut der MPG)

Matthias Scheffler
(Fritz-Haber Institut der MPG)

Numeric atom-centered local orbitals (NAO) are efficient basis sets for all-electron electronic structure theory. The locality of NAO's can be exploited to render (in principle) all operations of the self-consistency cycle $O(N)$. This is straightforward for 3D integrals using domain decomposition into spatially close subsets of integration points, enabling critical computational savings that are effective from $\sim$tens of atoms (no significant overhead for smaller systems) and make large systems (100s of atoms) computationally feasible. Using a new all-electron NAO-based code,$^1$ we investigate the quantitative impact of exploiting this locality on two distinct classes of systems: Large light-element molecules [Alanine-based polypeptide chains (Ala)$_n$], and compact transition metal clusters. Strict NAO locality is achieved by imposing a cutoff potential with an onset radius $r_c$, and exploited by appropriately shaped integration domains (subsets of integration points). Conventional tight $r_c\le$~3{\AA} have no measurable accuracy impact in (Ala)$_n$, but introduce inaccuracies of 20-30 meV/atom in Cu$_n$. The domain shape impacts the computational effort by only 10-20~\% for reasonable $r_c$. \newline $^1$ V. Blum, R. Gehrke, P. Havu, V. Havu, M. Scheffler, \emph{The FHI Ab Initio Molecular Simulations (aims) Project}, Fritz-Haber-Institut, Berlin (2006).

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.MAR.J19.8