# DFTB Manual 2024.1¶

The DFTB engine implements Density Functional based Tight-Binding methods, which can be viewed as computationally very efficient approximations to density functional theory (DFT). As such it is a good engine for computationally fast calculations that still include quantum effects. It can be used for molecules and for systems of any periodicity (3D, 2D and 1D).

**Graphical user interface (GUI) tutorials:**

**Table of Contents:**

- General
- AMS driver’s tasks and properties
- Model Hamiltonians
- Spectroscopy and properties
- Electronic transport (NEGF)
- Charge transport (transfer integrals)
- Examples
- Model Hamiltonians
- Example: SCC-DFTB aspirin
- Example: Smeared Fermi-Dirac occupations
- Example: Periodic aspirin
- Example: GO aspirin DFTB-SCC
- Example: DFTB3 CH3COO-
- Example: DFTB3 dispersion
- Example: DFTB3 dispersion periodic
- Example: Unpaired electrons cyclobutadiene
- Example: Spin polarized O2
- Example: Orbital dependent spin-polarized CH
- Example: NaCl fractional coordinates
- Example: NaCl slab
- Example: OH- noSCC
- Example: OH- SCC
- Example: Single Point H2 MOF
- Example: Single point COF5
- Example: Single point COF5, 2D
- Example: Single point COF5, 3D
- Example: H+
- Example: geometry optimizations in solution
- Example: Precision: k-space integration
- Example: External potential at nuclei
- Example: Restart DFTB
- Example: System input from file

- Geometry Optimization
- Example: GO formaldehyde noSCC
- Example: GO formaldehyde SCC
- Example: GO H3COO- DFTB3
- Example: GO cyclobutadiene spin-polarized
- Example: GO cyclobutadiene unpaired electrons
- Example: GO ethane 0D, 1D, 2D, 3D
- Example: GO poly-ethyleen
- Example: Restarting a geometry optimization
- Example: GO with constraints
- Example: GO with restraints
- Example: geometry optimizations: automations
- Example: Geometry optimization for an excited state
- Example: Geometry optimization following a specific excited state

- PESScan, Linear Transit, Transition State, NEB
- Electronic structure of periodic systems
- Excited States
- Example: Fullerene excitations
- Example: Excitations Ir(ppy)3
- Example: Excitations Davidson algorithm
- Example: Excitations transition charges on the fly
- Example: Excitations exact diagonalization
- Example: Excited state gradients: plams
- Example: Excitations SOT filter
- Example: Orbital dependent DFTB: Excitations
- Example: Excitations benchmark
- Example: Test parallelization

- Vibrations, IR spectra, Normal Modes, VCD
- Example: GO and frequencies aspirin
- Example: Normal modes (frequencies) for aspirin
- Example: Frequencies H2O
- Example: Frequencies OH-
- Example: Frequencies H2 slab
- Example: GO and frequencies C60
- Example: Excited states frequencies
- Example: Vibration resolved electronic spectrum: plams
- Example: Vibrational circular dichroism

- Phonons
- Stress tensor, Elasticity
- Molecular Dynamics
- Electronic transport, NEGF
- Analysis

- Model Hamiltonians
- Parameterizations
- Required citations
- References
- Keywords
- KF output files