DFTB – Neu in DFTB 2017

Neu in DFTB 2017

Im Folgenden sehen Sie einen Überblick über die neuen Schlüsselfunktionen der jeweiligen Version.

Neu in DFTB 2017

Neu in DFTB 2016

Scripting

  • ASE interfaced with the ADF modeling suite programs 
    The Atomic Simulation Environment (ASE) tool collection suite was designed as a flexible, easy-to-use, and customizable approach for the manipulation of quantum chemical models as well as for setting up and running the calculations required and for the analysis of the final results. D. Coupry and T. Soini at SCM have built ASE calculators for the main codes in the ADF Modeling Suite, thus opening up several of the methods in ASE.
  • PLAMS: Python Library for Automating Molecular Simulation 
    The PLAMS Python library, developed at SCM by Michał Handzlik, aims at facilitating scripting and work-flow automation in molecular modeling. PLAMS takes care of input preparation, job execution, file management and output processing and comes with interfaces to ADF, BAND and DFTB. SCM is making PLAMS available to the community as open-source (LGPL), contact SCM for details. Together with the related pyADF project led by Prof. Christoph Jacob, PLAMS is one of the components in the ongoing open-source project Computational Chemistry made Easy , led by Prof. Lucas Visscher, in which SCM also participates (contact Prof. Visscher or SCM for more information).
  • FlexMD (Flexible multi-scale Molecular Dynamics simulation): new features 
    FlexMD is a python library developed by Rosa Bulo's group at Utrecht University for molecular dynamics, specialized in multi-scale simulations. It is currently an expert option that requires scripting experience. The 2016 release includes a tabulated PBE-based force field for water suitable for QM/MM simulations. The center of the QM region can now also be defined more flexibly, e.g. as the position of a hydronium or hydroxide ion, important for simulating proton transfer processes.
  • adfprep and adfreport : New features for the command line tools adfprep (job preparation) and adfreport (results extraction):
    • Support for ADF, BAND, ReaxFF, DFTB, UFF, Mopac
    • Fragment support
    • Geometry changes, modify atom types, add groups
    • Support for SDF files

Neu in DFTB 2014

  • TD-DFTB excitation energies
    DFTB now allows excited state calculations for molecular systems using single orbital transitions as well as time-dependent DFTB. Singlet-singlet as well as singlet-triplet excitations can be calculated. A filter can be used to reduce computational costs, for example by using only single orbital transitions that have a minimal oscillator strength. The PRIMME library is used for finding the lowest eigenvalues of a matrix with the Davidson method.
  • Constrained optimizations
    Geometry optimizations can be constrained with constraints for the distance between two atoms, an angle defined by three atoms, or a dihedral angle defined by four atoms.
  • QUASINANO2013.1 parameters
    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.
  • Density matrix purification and sparse matrix algebra
    An alternative way to compute the density matrix corresponding to a given Hamiltonian is by means of the density matrix purification method. This method scales linearly with the system size when the Hamiltonian matrix is sparse and the HOMO-LUMO gap is large enough. This makes it especially useful for modeling large insulator or semi-conductor systems.
  • Conductance
    The conductance program has been added. It is a program to calculate coherent transport in extended junctions consisting of two semi-infinite electrodes separated by a molecule using the DFTB method combined with the nonequilibrium Green's Function (NEGF) formalism.

Neu in DFTB 2013

  • Car-Parrinello (experimental feature)
  • Conjugate gradients geometry optimization
  • Visualization of DFTB orbitals (only for "demo" parameters)
  • Partial density of states, PDOS
  • D3-BJ van der Waals dispersion correction added
  • (Parallel) performance improvements
  • 3OB parameters for DFTB3 method included

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