Linear scaling DFT calculations for large tungsten systems using an optimized local basis. (May 2018)

• Record Type: Journal Article
• Authors: Mohr, Stephan; Eixarch, Marc; Amsler, Maximilian; Mantsinen, Mervi J.; Genovese, Luigi
• Is Part Of: Nuclear materials and energy. Volume 15(2018)
• Page Start: 64
• Page End: 70
• Publication Date: 2018-05
• Subjects: Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2018.01.002
• Languages: English
• ISSNs: 2352-1791

Abstract

Highlights: The code BigDFT allows to perform accurate DFT simulations for large metallic systems. Calculations for Tungsten systems containing several thousand atoms were conducted. There is no computational bottleneck related to the metallic character. Our findings open up promising possibilities for multiscale modelling of very large systems. Abstract: Density functional theory (DFT) has become a standard tool for ab-initio simulations for a wide range of applications. While the intrinsic cubic scaling of DFT was for a long time limiting the accessible system size to some hundred atoms, the recent progress with respect to linear scaling DFT methods has allowed to tackle problems that are larger by many orders of magnitudes. However, as these linear scaling methods were developed for insulators, they cannot, in general, be straightforwardly applied to metals, as a finite (electronic) temperature is needed to ensure locality of the density matrix. In this paper we show that, once finite electronic temperature is employed, the linear scaling version of the BigDFT code is able to exploit this locality to provide a computational treatment that scales linearly with respect to the number of atoms of a metallic system. We provide prototype examples based on bulk Tungsten, which plays a key role in finding safe and long-lasting materials for Fusion Reactors; however we do not expect any major obstacles in extending this work to cover other metals. We believe that such an approach might help in opening the path towards novel approaches for investigating the electronic structure of such materials, in particular when large supercells are required.