KITE: high-performance accurate modelling of electronic structure and response functions of large molecules, disordered crystals and heterostructures

TL;DR

KITE is an open-source, high-performance software for large-scale electronic structure and quantum transport simulations, capable of handling systems with tens of billions of atomic orbitals efficiently and accurately.

Contribution

It introduces a scalable, efficient spectral Green's function approach integrated into a user-friendly Python interface for large-scale quantum simulations.

Findings

Supports simulations of disordered materials and heterostructures

Achieves nearly linear scaling in multi-threaded performance

Enables detailed analysis of electronic and optical properties

Abstract

We present KITE, a general purpose open-source tight-binding software for accurate real-space simulations of electronic structure and quantum transport properties of large-scale molecular and condensed systems with tens of billions of atomic orbitals (N~10^10). KITE's core is written in C++, with a versatile Python-based interface, and is fully optimised for shared memory multi-node CPU architectures, thus scalable, efficient and fast. At the core of KITE is a seamless spectral expansion of lattice Green's functions, which enables large-scale calculations of generic target functions with uniform convergence and fine control over energy resolution. Several functionalities are demonstrated, ranging from simulations of local density of states and photo-emission spectroscopy of disordered materials to large-scale computations of optical conductivity tensors and real-space wave-packet propagation in the presence of magneto-static fields and spin-orbit coupling. On-the-fly calculations of real-space Green's functions are carried out with an efficient domain decomposition technique, allowing KITE to achieve nearly ideal linear scaling in its multi-threading performance. Crystalline defects and disorder, including vacancies, adsorbates and charged impurity centers, can be easily set up with KITE's intuitive interface, paving the way to user-friendly large-scale quantum simulations of equilibrium and non-equilibrium properties of molecules, disordered crystals and heterostructures subject to a variety of perturbations and external conditions.