# DFTBaby: A software package for non-adiabatic molecular dynamics simulations based on long-range corrected tight-binding TD-DFT(B)

## TL;DR

DFTBaby is a software package that enables non-adiabatic molecular dynamics simulations using charge-consistent tight-binding DFT with long-range correction, facilitating studies of excited states and non-adiabatic effects.

## Contribution

It introduces a new software tool integrating long-range corrected tight-binding TD-DFT for non-adiabatic molecular dynamics simulations.

## Key findings

- Successfully applied to polyfluorene excited states
- Provides analytic gradients and non-adiabatic couplings
- Available as open-source software

## Abstract

A software package, called DFTBaby, is published, which provides the electronic structure needed for running non-adiabatic molecular dynamics simulations at the level of charge-consistent tight-binding DFT. A long-range correction is incorporated to avoid spurious charge transfer states. Excited state energies, their analytic gradients and scalar non-adiabatic couplings are computed using tight-binding TD-DFT. These quantities are fed into a molecular dynamics code, which integrates Newton's equations of motion for the nuclei together with the electronic Schr\"{o}dinger equation. Non-adiabatic effects are included by surface hopping. As an example, the program is applied to the optimization of excited states and non-adiabatic dynamics of polyfluorene. The python and Fortran source code is available at http://www.dftbaby.chemie.uni-wuerzburg.de/.