Speaker
Description
Scanning tunneling microscopy and spectroscopy (STM/STS) provide powerful tools for probing electronic properties at the atomic scale. On the theoretical side, density functional theory (DFT) and Wannier-based methods allow realistic first-principles descriptions of complex nanosystems. However, modeling nonequilibrium transport remains a significant challenge, especially in superconducting hybrid systems where particle-hole correlations must be treated explicitly. Accurate and efficient theoretical simulations are therefore essential for interpreting experimental measurements and understanding the underlying transport mechanisms.
Here, we present a workflow that combines Wannierized first-principles electronic structure calculations with the nonequilibrium Green's function formalism to enable efficient simulations of STM experiments [1]. This approach builds upon standard DFT packages to construct compact transport Hamiltonians that retain the electronic properties of realistic materials. Superconductivity is incorporated through an effective pairing potential within the Nambu-spinor formalism, while the coupling to the STM tip and substrate electrodes is treated within the wide-band limit approximation.
Within this framework, transport quantities such as current-voltage characteristics are evaluated in closed analytical form. This substantially reduces the computational cost of spectroscopic calculations. The method provides a unified and computationally efficient approach for modeling superconducting hybrid nanostructures featuring spin-orbit coupling, magnetic textures, and spin polarization. Representative applications demonstrate its robustness and versatility for both simple model systems and realistic ab initio molecular structures relevant to modern STM experiments.
[1] O. Moreno Segura et al., manuscript in preparation (2026).