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O: Fachverband Oberflächenphysik

O 10: Focus Session: Frontiers of Electronic-Structure Theory – Advances in Time-Dependent and Nonequilibrium Ab Initio Methods II

O 10.8: Talk

Monday, March 18, 2024, 16:45–17:00, HE 101

Exploiting Crystal Symmetry in the LAPW Method — •Mara Voiculescu, Sven Lubeck, and Claudia Draxl — Humboldt-Universität zu Berlin, Berlin, Germany

In the framework of density functional theory (DFT) calculations, the linearized augmented planewave (LAPW) method uses a dual representation for physical quantities such as the charge density and potential. This approach consists of a spherical harmonic expansion inside the so-called muffin-tin spheres around the nuclear positions and a planewave expansion in between them. The direct implementation results in a large number of expansion coefficients which need to be computed. Exploiting symmetry by employing group-theoretical methods simplifies the mathematical description and therefore reduces computational expenses. Consequently, symmetry can be used to speed up the setup of the Hamiltonian matrix, while at the same time resulting in better numerical precision. We implement this approach in the all-electron full-potential computer package exciting [1], by using symmetrized spherical harmonics (lattice harmonics) and planewaves (stars), yielding a considerable computational speedup for a variety of different materials.

[1] A. Gulans et al., J. Phys. Condens. Matter 26, 363202 (2014).

Keywords: DFT; LAPW; exciting; Symmetry