Density-functional theory (DFT) is a widespread method for simulating the quantum-chemical behavior of electrons in matter. This talk presents our package DFTK, which aims to provide a joint platform accessible to different scientific communities. The quantum-chemical simulation of electronic structures is an established approach in materials research. The desire to tackle even bigger systems and more involved materials, however, keeps posing challenges with respect to physical models, reliability, and performance of methods such as DFT. With DFTK (https://dftk.org/) we provide a Julia package for DFT, which aims to be fast enough for practical calculations, but also flexible to support toy problems for mathematical development in the field. Contents 00:00 Welcome! 01:14 Overview of the talk 01:33 Why care about electrons? 02:55 Aren't experiment good enough? 04:05 Electronic structure theory 05:36 Problem: computing integral over high-dimension space 06:34 Density Functional Theory (DFT) 07:35 Solving DFT: self-consistent field procedure 08:40 Landscape of DFT codes 09:12 Why do we bother with developing DFTK.jl? 12:01 Overview of DFTK.jl 13:29 The only way we can manage it awesome Julia community and ecosystem 14:35 Lowering the entrance barrier for researches 17:44 High-throughput screening 20:41 A posteriori error analysis in DFT 22:23 A posteriori error analysis with DFTK.jl 24:00 A posteriori error analysis, first results 24:26 Quick look at SCF algorithms 24:43 Summary and outlook 25:40 Acknowledgements S/O to https://github.com/KZiemian for the video timestamps! Want to help add timestamps to our YouTube videos to help with discoverability? Find out more here: https://github.com/JuliaCommunity/YouTubeVideoTimestamps Interested in improving the auto generated captions? Get involved here: https://github.com/JuliaCommunity/YouTubeVideoSubtitles