Dresden 2026 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 1: Optical Properties I

HL 1.11: Talk

Monday, March 9, 2026, 12:15–12:30, POT/0006

Accurate computation of Berry connection purely limited by basis set completeness — Martin Thümmler¹, •Alexander Croy¹, Thomas Lettau², Ulf Peschel^2,3, and Stefanie Gräfe^1,3,4 — ¹Institute of Physical Chemistry, Friedrich Schiller University Jena — ²Institute of Condensed Matter Theory and Optics, Friedrich Schiller University Jena — ³Abbe School of Photonics, Friedrich Schiller University Jena — ⁴Fraunhofer Institute for Applied Optics and Precision Engeneering Jena

Wannierization provides a reliable framework for interpolating operator matrix elements in the Brillouin zone. This Fourier-type interpolation of the matrix elements of k-local operators, e.g., the Hamiltonian, is well understood. However, the Berry connection is computed from the overlap matrices of the cell periodic parts of the Bloch functions with different k and hence non-local. So far, all proposed interpolation schemes do not account for the matrix structure of the overlap matrices, but treat the matrix elements as independent when computing the Berry connection. In this work, we propose a consistent interpolation scheme based on the matrix logarithm. Its accuracy is only limited by the basis set incompleteness of the considered bands in the ab-initio calculation. The quality of the new interpolation scheme is demonstrated by an improved agreement between the velocity and momentum operator over the full Brillouin zone. As an application, we demonstrate how this refinement impacts the predicted linear and non-linear optical properties of semiconductors.

Keywords: Berry Connection; Wannier function; Dipole operator