Assess the accuracy of single-pole truncation for the screened interaction

Investigate how truncating the pole representation of the correlated screened interaction W_c to a single pole affects the accuracy of real-world GW calculations, and determine the accuracy of the M=1 truncation within the pole-representation framework.

Background

The paper relates its general pole-representation framework to the plasmon-pole approximation, in which the frequency dependence of the correlated screened interaction is reduced to one positive-frequency pole and its negative-frequency conjugate. Although such truncations are widely used in practical GW calculations, the choice of pole frequency and residue is not unique, and the consequences of the truncation for realistic calculations remain an active research issue.

The paper specifically notes that its own pole framework could be truncated to a single pole for the correlated screened interaction W_c, but that this test has not yet been carried out. Establishing the resulting accuracy would clarify whether the general systematically improvable representation can reproduce the practical efficiency of the plasmon-pole approximation without sacrificing reliable spectral information.

References

The extent to which the truncation to a single pole reduces the accuracy of real-world calculations is a topic of research, and a truncation of our scheme to $M=1$ for $W_c$ has not yet been attempted.

— Real-Frequency Diagrammatics with Pole Representations  (2609.26703 - Farid et al., 22 Sep 2026) in Section Discussion, subsection “The Plasmon Pole approximation”