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.. _features and algorithms:
=======================
Features and algorithms
=======================
Quick links to all features:
.. list-table::
* - :ref:`Plane-waves <manual_mode>`
- :ref:`Finite-difference <manual_stencils>`
- :ref:`LCAO <lcao>`
* - :ref:`XC-functionals <xc>`
- :ref:`DFT+U <hubbardu>`
- :ref:`GLLB-SC <band_gap>`
* - :ref:`DOS <dos>`
- :ref:`STM <stm tutorial>`
- :ref:`Wannier functions <wannier>`
* - :ref:`delta-SCF <dscf>`
- :ref:`XAS <xas>`
- :ref:`Jellium <jellium>`
* - :ref:`TDDFT <timepropagation>`
- :ref:`LRTDDFT (molecules) <lrtddft>`
- :ref:`LRTDDFT (extended systems) <df_theory>`
* - :ref:`RPA-correlation <rpa>`
- :ref:`GW <gw_theory>`
- :ref:`BSE <bse theory>`
* - :ref:`Parallelization <parallel_runs>`
- :ref:`Continuum Solvent Model <continuum_solvent_model>`
- :ref:`point groups`
This Page gives a quick overview of the algorithms used. We have
written some :ref:`papers <faq>` about the implementation,
where *all* the details can be found.
**Introduction**
Using the projector-augmented wave (PAW)
method [Blo94]_, [Blo03]_ allows us to get rid of the core
electrons and work with soft pseudo valence wave functions. The
pseudo wave functions don't need to be normalized - this is important
for the efficiency of calculations involving 2. row elements (such as
oxygen) and transition metals. A further advantage of the PAW method
is that it is an all-electron method (frozen core approximation) and
there is a one to one transformation between the pseudo and
all-electron quantities.
**Description of the wave functions**
Pseudo wave functions can be described in three ways:
Plane-waves (PW):
Expansion in plane-waves.
Linear combination of atomic orbitals (LCAO):
Expansion in atom-centered basis functions.
Finite-difference (FD):
Uniform real-space grids.
**ASE interface**
The code has been designed to work together with the atomic
simulation environment (`ASE <https://wiki.fysik.dtu.dk/ase>`_). ASE provides:
* Structure optimization.
* Molecular dynamics.
* Nudged elastic band calculations.
* Maximally localized Wannier functions.
* Scanning tunneling microscopy images.
**Open Software**
GPAW is released under the :xkcd:`GNU Public License <225>`
version 3 or any later version. See the file :git:`LICENSE` which
accompanies the downloaded files, or see the license at GNU's web
server at https://www.gnu.org/licenses/. Everybody is invited to
participate in using and :ref:`developing the code <devel>`.
.. figure:: carlsberg.png
:width: 12cm
September 2003 - August 2005: Sponsored by The `Carlsberg Foundation`_
(artwork by P. Erhart)
.. _Carlsberg Foundation: https://www.carlsbergfondet.dk
.. [Blo94] P. E. Blöchl,
Phys. Rev. B 50, 17953 (1994)
.. [Blo03] P. E. Blöchl, C. J. Först and J. Schimpl,
Bull. Mater. Sci, 26, 33 (2003)
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