Recent Developments in DFTB+, a Software Package for Efficient Atomistic Quantum Mechanical Simulations

DFTB+ is a flexible,
open-source software package developed
by
its community, designed for fast and efficient atomistic quantum mechanical
simulations. It employs various methods that approximate density functional
theory (DFT), such as density functional-based tight binding (DFTB)
and the extended tight binding (xTB) approach allowing simulations
of large systems over extended time scales with reasonable accuracy,
while being significantly faster than traditional ab initio methods.
In recent years, several new extensions of the DFTB method have been
developed and implemented in the DFTB+ program package in order to
improve the accuracy and generality of the available simulation results.
In this paper, we review those enhancements, show several use case
examples and discuss the strengths and limitations of its features.