Lindhard and RPA susceptibility computations in extended momentum space in electron doped cuprates

TL;DR

This paper introduces an efficient FFT-based method to compute Lindhard susceptibility in extended momentum space, demonstrated on electron-doped cuprates, aiding interpretation of inelastic X-ray scattering data.

Contribution

The paper presents a new approximation method for calculating Lindhard susceptibility using FFT and real space functions, applicable over multiple Brillouin zones.

Findings

Computed susceptibility for Nd$_{2-x}$Ce$_{x}$CuO$_{4}$ over several Brillouin zones.

Method improves efficiency of susceptibility calculations in periodic systems.

Results assist in interpreting inelastic X-ray scattering spectra.

Abstract

We present an approximation for efficient calculation of the Lindhard susceptibility $\chi^{L}(q,\omega)$ in a periodic system through the use of simple products of real space functions and the fast Fourier transform (FFT). The method is illustrated by providing $\chi^{L}(q,\omega)$ results for the electron doped cuprate Nd$_{2-x}$Ce$_{x}$CuO$_{4}$ extended over several Brillouin zones. These results are relevant for interpreting inelastic X-ray scattering spectra from cuprates.