Automatic Generation of Density-Fitting Auxiliary Basis Sets for All-Electron Dirac-Kohn-Sham Calculations

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Relativistic effects, including spin-orbit coupling, are vital for accurately describing molecules with heavy elements.
• Heavy elements are crucial in fields like catalysis and quantum technologies.
• Accurate computational methods are needed to model these systems.

Purpose of the Study:

• To present a general workflow for the automatic generation of auxiliary density basis sets for all elements (H to Og).
• To facilitate the widespread application of relativistic Dirac-Kohn-Sham calculations.
• To improve the description of relativistic effects in molecules containing heavy elements.

Main Methods:

• An even-tempered scheme, inspired by previous nonrelativistic DFT work, is used for automatic generation.
• The algorithm utilizes information from the principal relativistic spinor basis set (exponents, angular momentum values).
• A strategy is included to handle the high angular momentum of electrons in heavy and superheavy elements.

Main Results:

• The workflow enables automated testing on a dataset of ~300 molecules across the periodic table.
• Generated auxiliary basis sets demonstrate high accuracy, with Coulomb energy errors in the micro-hartree range.
• The accuracy is comparable to nonrelativistic density fitting methods.

Conclusions:

• The developed automatic workflow is general and applicable to all elements.
• Future work will focus on optimizing auxiliary basis sets for relativistic approaches including exact exchange.
• This advancement is critical for accurately predicting spectroscopic properties and spin dynamics in heavy element systems.