SIAM MS: Using the density-functional toolkit to design black-box DFT methods

After being moved by one year due to the pandemic, the last two weeks (from 17th to 28th May) the SIAM materials science conference finally took place in virtual form. Unfortunately this meant that the conference was scheduled in parallel to the SIAM Linear Algebra virtual conference, where I also presented (blog article), which made my past two weeks rather busy.

At SIAM Materials I was invited to talk in the Minisymposium Numerics of electronic structure calculations, which was organised by the steering committee of the GAMM activity group moansi (Modelling, Analysis and Simulation of Molecular Systems). Besides interesting sessions about some mathematical insights to electronic-structure methods, this gave the mini the additional feature of a spring gathering for the usual crowd of the activity group, which I already had the pleasure to meet at previous moansi workshops.

In my talk I gave a broad overview of the recent projects we realised with the density-functional toolkit for making self-consistent field calculations for density-functional theory more robust and reliable. Apart from our work on preconditioning inhomogeneous systems with the LDOS preconditioner I also presented first work-in-progress results on an adaptive damping strategy we recently came up with. The idea of our method is to use a line search based on an approximate quadratic model for cases where a proposed SCF step is not successful (i.e. increases energy and SCF residual). This firstly allows to automatically choose the damping parameter (instead of requiring the user to choose one by trial and error). Secondly it makes the SCF procedure more robust, especially for tricky cases. For example in our experiments on Heusler alloys our adaptive damping approach was the only method that managed to converge on some cases.

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Using the density-functional toolkit (DFTK) to design black-box methods in density-functional theory Creative Commons License