Linear scaling DFT calculations for large Tungsten systems using an optimized local basis

Abstract

Density Functional Theory (DFT) has become the quasi-standard 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 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. 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.

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• Thermal and Oxidation Stability of Ti${}_x$W${}_{1-x}$ Diffusion Barriers Investigated by Soft and Hard X-ray Photoelectron Spectroscopy
• Real-space formulation of the stress tensor for $\mathcal{O}(N)$ density functional theory: application to high temperature calculations
• Modular implementation of the linear and cubic-scaling orbital minimization methods in electronic structure codes using atomic orbitals
• Structure Optimization with Stochastic Density Functional Theory
• Systematic lowering of the scaling of Monte Carlo calculations by partitioning andsubsampling