Insights into hybrid functional parameters from the XC kernel

Often the bulk properties of materials like the lattice constant (interparticle distance and/or separation), stress tensor, etc., at high pressures and temperatures differ significantly from those under ambient conditions. The situation is particularly unsatisfactory for warm dense matter (WDM), where basic atomic properties like an atomization energy become ill defined and where bulk properties such as bulk moduli cannot be accurately measured due to extreme conditions. This calls for an approach that allows the non-empirical choice of the parameters of hybrid functionals without employing properties limited to ambient conditions. At the same time, it is preferable that such an approach have some connection to properties that are well defined and measurable in experiments across temperature and pressure regimes. We report that the static XC kernel can serve as a theoretical device for constructing hybrid functionals that are non-empirical and that apply for both solid-state systems and WDM [1-3].

[1] Zhandos A. Moldabekov, Mani Lokamani, Jan Vorberger, Attila Cangi, and Tobias Dornheim, Non-empirical Mixing Coefficient for Hybrid XC Functionals from Analysis of the XC Kernel, The Journal of Physical Chemistry Letters 14, 1326–1333 (2023), https://doi.org/10.1021/acs.jpclett.2c03670

[2] Zhandos Moldabekov, Maximilian Boeme, Jan Vorberger, David Blaschke, and Tobias Dornheim, Ab initio Static Exchange-Correlation Kernel across Jacob’s Ladder without functional derivatives, Journal of Chemical Theory and Computation 19, 1286–1299 (2023), https://doi.org/10.1021/acs.jctc.2c01180

[3] Zhandos A. Moldabekov, Mani Lokamani, Jan Vorberger, Attila Cangi, Tobias Dornheim, Assessing the accuracy of hybrid exchange-correlation functionals for the density response of warm dense electrons, J. Chem. Phys. 158, 094105 (2023)
https://doi.org/10.1063/5.0135729