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MM: Fachverband Metall- und Materialphysik

MM 8: Development of Computational Methods: Diverse Topics and Machine Learning

MM 8.1: Talk

Monday, March 27, 2023, 15:45–16:00, SCH A 251

Adaptively Compressed Exchange in LAPW — •Davis Zavickis, Kristians Kacars, Janis Cimurs, and Andris Gulans — Electronic Structure Group, University of Latvia, Jelgavas st. 3, LV-1004, Riga, Latvia

We address precision and reproducibility issues in DFT calculations with hybrid functionals. Linearized augmented plane waves (LAPW) method currently serves as the de facto reference tool within the electronic structure community. In the current implementation of the Fock exchange in LAPW, the total and band energies depend on the number of orbitals used. We overcome these issues by implementing the adaptively compressed exchange (ACE) method [Lin Lin, J. Chem. Comput., 2016, 12, 5] in exciting code that introduces a low rank approximation and apply it to light atoms, molecules and solids [D. Zavickis et al., Phys. Rev. B., 2022, 106, 165101]. In case of atoms and molecules, we show that ACE leads to highly precise total energies which are within a few microhartrees off the results obtained by multi-resolution analysis method. In solids we calculate band structures that are compared with other all-electron hybrid implementations. Lastly, we apply optimizations and fine tuning to ACE, analyze its complexity and computational performance by comparing it to the previous Fock-exchange implementation in the exciting code.