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O: Fachverband Oberflächenphysik

O 50: Electronic structure theory II

O 50.7: Vortrag

Dienstag, 10. März 2026, 16:00–16:15, TRE/PHYS

Brillouin zone sampling in ONETEP — •Chengcheng Xiao, Peter Haynes, and Arash Mostofi — Department of Material, Imperial College London, London SW7 2AZ, United Kingdom

ONETEP is a parallelised linear-scaling density-functional theory (DFT) simulation software package designed for large-scale calculations of properties of materials. It was engineered under the premise that, for self-consistent calculations of systems with thousands of atoms, the Brillouin zone only needs to be sampled at its centre - the Gamma-point.

Whilst this is a suitable approximation for large systems, it often leads to the unnecessary use of large supercells of structures where periodicity can be exploited. For those systems, a more suitable method is to sample the Brillouin zone along the periodic directions.

In this work, we introduce a new Brillouin zone sampling technique in ONETEP where the localisation constraint imposed on the basis functions is selectively lifted along the periodicity directions, making it possible to perform a ``hybrid'' calculation where the best scaling can be achieved by incorporating both Brillouin zone sampling and linear-scaling techniques. Furthermore, if the unit cell is small along all directions, all localisation constraints can be lifted, which effectively turns ONETEP into a plane-wave code. This enables us to compare the algorithmic accuracy of ONETEP to other DFT codes on the same footing. These developments enable much more efficient calculations on short and intermediate-scale periodic systems, such as bulk crystals, nanowires, surfaces, and interfaces.

Keywords: ONETEP; Brillouin zone sampling; Linear-scaling DFT