C-BerryANC: A first-principle C++ code to calculate Berry Curvature dependent anomalous Nernst conductivity in any material

TL;DR

The paper introduces C-BerryANC, a fast, accurate C++ code for calculating Berry curvature-dependent anomalous Nernst conductivity directly from first-principles electronic structure data, applicable to any material.

Contribution

It provides a first-principles, efficient, and reliable computational tool for ANC calculation that overcomes limitations of Wannier interpolation methods.

Findings

Code accurately reproduces known ANC values for benchmark materials.

Parallelized over k-points for efficiency in dense mesh calculations.

Stores band-resolved Berry curvature components for flexible post-processing.

Abstract

The anomalous Nernst conductivity (ANC) is a key transport property in magnetic and topological materials, arising from the Berry curvature ($\boldsymbol\Omega$) of electronic bands. It offers deep insight into the underlying topology and thermoelectric behavior. While Wannier interpolation have become popular for calculating ANC due to their computational efficiency, their accuracy critically depends on the quality of the Wannierization, which can be challenging for entangled bands or materials with complex band crossings. These limitations highlight the need for a direct first-principles approach to reliably compute ANC from ab-initio electronic structures. Here, we present a C++ based code named C-BerryANC that calculates $\boldsymbol\Omega$-dependent ANC by directly using the eigenvalues and momentum-matrices obtained from DFT calculations. Presently, the code is interfaced with WIEN2k package which uses all-electron approach and full-potential linearized augmented plane wave (FP-LAPW) based method. For efficiently handling dense k-mesh, calculation of $\boldsymbol\Omega$ is made parallel over k-points using the OpenMP method. Additionally, the code stores band-resolved components of $\boldsymbol\Omega$ in binary files thereby reducing the memory occupancy and providing fast post-process option to compute ANC for any range of chemical potential and temperature values. Also, as compilation of C++ modules produce executable files which are in machine level language, computational speed of C-BerryANC is very fast. The code is benchmarked over some well-known materials exhibiting ANC. These includes- Pd, Fe$_3$Al & Co$_2$FeAl. The obtained values of ANC is found to in good agreement with the previously reported data. This highlights the accuracy, efficieny and reliability of the C-BerryANC code.