Parameter files¶

Available parameter sets¶

Dresden

The so called Dresden set of DFTB parameter files available in the ADF package were designed by J. Frenzel, A.F. Oliveira, N. Jardillier, T. Heine, and G. Seifert, mainly at the Technische Universitt in Dresden, Germany, see also some additional information about the generation of these parameter files. These parameter files are kept in the directory $ADFHOME/atomicdata/DFTB/Dresden.

QUASINANO

The QUASINANO2013.1 set of DFTB parameter files available in the ADF package are designed by Mohammad Wahiduzzaman et al. contains parameters for a large part of the periodic table (no f-elements). Note that the QUASINANO2013.1 set only contains the electronic part of the interaction, so that only the spectrum for a given geometry can be calculated, but no total energy, and thus also no forces. These parameters can be used in TDDFTB calculations, for example.

The QUASINANO2015 parameter set extends the QUASINANO2013.1 parameter set, and includes terms that are needed to compute the total energy and its gradient.

DFTB.org

The DFTB implementation shipped by SCM provides the most up-to-date parameter sets available on the DFTB.org website. The following sets are currently shipped:

• 3ob-3-1 (Br, C, Ca, Cl, F, H, I, K, Mg, N, Na, O, P, S, Zn)
• mio-0-1 and mio-1-1 (H, C, N, O, S, P): for organic molecules
• pbc-0-3 (Si, F, O, N, C, H, Fe): for solid and surfaces
• matsci-0-3 (Al, Si, Cu, Na, Ti, Ba): for various compounds in material science

In addition, the following extension sets are provided to the mio set (either version 0-1 or 1-1):

• hyb-0-1 (Ag, Ga, As, Si) + mio-0-1: for organic and inorganic hybrid systems
• chalc-0-1 (As, S) + mio-0-1: for Chalcogenide glasses
• miomod-hh-0-1 + mio-1-1: contains a modified parameter set for H2
• miomod-nh-0-1 + mio-1-1: contains a modified parameter set fo N-H to improve N-H binding energies
• tiorg-0-1 (Ti-(C, H, N, O, S, Ti)) + mio-0-1 : for Ti bulk, TiO2 bulk, TiO2 surfaces, and TiO2 with organic molecules
• trans3d-0-1 (Sc, Ti, Fe, Co, Ni)) + mio-0-1: Transition metal elements for biological systems
• znorg-0-1 (Zn-(C, H, N, O, S, Zn)) + mio-0-1: for Zn bulk, ZnO bulk, ZnO surfaces, and ZnO with organic molecules

We recommend to visit the DFTB.org web site for more detailed information about each set. Please note that our implementation of DFTB does not support parameter sets files containing f-functions, such as the “rare” set.

Installing additional DFTB.org parameter files¶

To install new parameter sets released by the DFTB.org website in the future, we recommend the following procedure

• Unpack the tar.gz file containing the parameters (for example, newset-0-1.tar.gz) with the command tar -C $ADFRESOURCES/DFTB/DFTB.org -xzvf newset-0-1.tar.gz.
• Make sure the files have the name in the format X-Y.skf, with X and Y element symbols (for example, C-C.skf, C-H.skf, Al-H.skf). If this is not the case, rename the files to follow this naming.
• Take note of the new directory name created in $ADFRESOURCES/DFTB/DFTB.org while unpacking (for example, newset-0-1)

The new parameter set can be now specified with the key ResourcesDir

ResourcesDir DFTB.org/newset-0-1

Third Order parameter files¶

The parameter files for third-order evaluation are available under a separate license agreement. Contact our licensing department for more information. Third-order parametrization uses the values classified as “DFTB3 fit” in the reference paper (Gaus, Cui, and Elstner). The special parameters for DFTB3 (Hubbard derivatives and Zeta) are defined in file metainfo.yaml (see below).

metainfo.yaml¶

There should be a file named metainfo.yaml in each resources directory (see ResourcesDir), for example DFTB.org/3ob-1-1/metainfo.yaml. The file is in accordance with the YAML syntax convention. It contains necessary information required for DFTB calculation. An example with explanation comments (beginning with #) is shown here:

*# version info*
metainfo_version: 1

*# SCC models the current resources directory supports ("thirdorder" is aliased to "dftb3")
# possible models: noscc, scc, thirdorder*
supports: [ thirdorder ]

*# Hubbard derivatives for DFTB3, see DOI: 10.1021/ct300849w
# note: the list must be { } rather than [ ]*
Hubbard_derivatives:
    zeta: 4.000
    parameters: { H: -0.1857, C: -0.1492, N: -0.1535, O: -0.1575, P: -0.14, S: -0.11 }

*# magnetic Hubbard parameters for TD-DFTB, see DOI: 10.1103/PhysRevB.63.085108
# note: the list must be { } rather than [ ]*
magnetic_Hubbard:
    parameters: { H: -1.9700, C: -0.6180, N: -0.6940, O: -0.7590 }

*# London dispersion correction models*
dispersion:
*# default method to use if none is specified in the input script*
    default: D3-BJ
*# list of supported dispersion corrections*
    UFF:
    ULG:
    D2:
    D3-BJ:
*# D3-BJ dispersion parameters fitted by S. Grimme
# see: http://www.thch.uni-bonn.de/tc/index.php?section=downloadssubsection=DFT-D3*
        parameters: { s6: 1.0000, s8: 0.5883, a1: 0.5719, a2: 3.6017 }

*# references*
reference: |
    M. Gaus, A. Goez, M. Elstner
    "Parametrization and Benchmark of DFTB3 for Organic Molecules"
    J. Chem. Theory Comput. 2013, 9 (1), pp 338-354.

    M. Gaus, X. Lu, M. Elstner, Q. Cui
    "Parameterization of DFTB3/3OB for Sulfur and
     Phosphorus for Chemical and Biological Applications"
    J. Chem. Theory Comput. 2014, 10 (4), pp 1518-1537

*# references in short format*
short_reference: |
    [O-N-C-H] J. Chem. Theory Comput. 2013, 9, 338-354.
    [P-S] J. Chem. Theory Comput. 2014, 10, 1518-1537

*# web link*
url: http://www.dftb.org/parameters/download/3ob/3ob_2_1/

*# Slater-Koster files: "txtn" indicates encrypted, "txt" indicates unencrypted*
format: txtn