posted on 2023-12-13, 16:38authored byCan Liao, Eleftherios Lambros, Qiming Sun, Kenneth G. Dyall, Xiaosong Li
The
Dirac-Coulomb-Breit (DCB) operator is widely recognized for
its ability to accurately capture relativistic effects and spin-physics
in molecular calculations. However, due to its high computational
cost, there is a need to develop low-scaling approximations without
compromising accuracy. To tackle this challenge, it becomes essential
to gain a deeper understanding of the DCB operator’s behavior.
This work aims to explore local integral approximations, shedding
light on the locality of the parts of the charge-current distribution
due to the small component. In particular, we propose an atomic Breit
approximation that leverages an analysis of the behavior observed
in a series of gold chains. Through benchmark studies of metal complexes,
we evaluated the accuracy and performance of the proposed atomic Breit
approximation. This work provides a comprehensive understanding of
the behavior of the charge-current distribution in terms of its contributions
from its AO basis constituents, facilitating the development of low-scaling
methods that strike a balance between computational efficiency and
accuracy.