Editing VASP

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[[Image:Vasp_logo_1.png|right|alt=VASP logo]]

== DESCRIPTION ==
<p align="center" style="width:100%">
{| border="4" 
 |- 
 | &nbsp; &nbsp; '''VASP''' = '''V'''ienna '''''A'''b-Initio'' '''S'''imulation '''P'''ackage &nbsp; &nbsp;
 |}

The Vienna Ab initio Simulation Package (VASP) is a computer program for atomic scale materials modelling, e.g. electronic structure calculations and quantum-mechanical molecular dynamics, from first principles.

VASP computes an approximate solution to the many-body Schrödinger equation, either within density functional theory (DFT), solving the Kohn-Sham equations, or within the Hartree-Fock (HF) approximation, solving the Roothaan equations. Hybrid functionals that mix the Hartree-Fock approach with density functional theory are implemented as well. Furthermore, Green's functions methods (GW quasiparticles, and ACFDT-RPA) and many-body perturbation theory (2<sup>nd</sup>-order Møller-Plesset) are available in VASP.

In VASP, central quantities, like the one-electron orbitals, the electronic charge density, and the local potential are expressed in plane wave basis sets. The interactions between the electrons and ions are described using norm-conserving or ultrasoft pseudopotentials, or the projector-augmented-wave method.

To determine the electronic groundstate, VASP makes use of efficient iterative matrix diagonalisation techniques, like the residual minimisation method with direct inversion of the iterative subspace (RMM-DIIS) or blocked Davidson algorithms. These are coupled to highly efficient Broyden and Pulay density mixing schemes to speed up the self-consistency cycle.

: '''Obsolete description:''' VASP is a complex package for performing ab-initio quantum-mechanical molecular dynamics (MD) simulations using pseudopotentials or the projector-augmented wave method and a plane wave basis set. The approach implemented in VASP is based on the (finite-temperature) local-density approximation with the free energy as variational quantity and an exact evaluation of the instantaneous electronic ground state at each MD time step. VASP uses efficient matrix diagonalisation schemes and an efficient Pulay/Broyden charge density mixing. These techniques avoid all problems possibly occurring in the original Car-Parrinello method, which is based on the simultaneous integration of electronic and ionic equations of motion. The interaction between ions and electrons is described by ultra-soft Vanderbilt pseudopotentials (US-PP) or by the projector-augmented wave (PAW) method. US-PP (and the PAW method) allow for a considerable reduction of the number of plane-waves per atom for transition metals and first row elements. Forces and the full stress tensor can be calculated with VASP and used to relax atoms into their instantaneous ground-state.

== VERSIONS ==

In general, 2 major versions of VASP are currently available: '''VASP 4.6''' and a completely re-written and better equipped '''VASP 5.2'''.

''Beware, for some INCAR-file tags, different default values may be used. Together with he fact, that Fourier-transform (FFT) routines scale in a tricky way with the number of nodes,  etc. etc., it is very likely that the total energies of the same system calculated by different VASP versions are not equal.''

On [[tekla]] cluster, only VASP 4.6 is installed.

On [[tekla2]] cluster, both VASP 4.6 and VASP 5.2 (+ subversions) are available. Futhermore, versions with extra routines (modules suffixed by <TT>_VTST</TT>) or [[gamma-point-only]] binary (<TT>_GAMMA</TT>) are available here.

== LINKS & RESOURCES ==

1. Main developers' pages

: [http://cms.mpi.univie.ac.at/vasp/vasp/vasp.html Online-Manual (HTML/PDF)]

: [http://cms.mpi.univie.ac.at/vasp-workshop/slides/documentation.htm Lecture-Notes & Hands-On Sessions (HTML/PDF)]

: [http://cms.mpi.univie.ac.at/marsweb/ New Website (HTML)]

2. Other contributors / developers

: [http://theory.cm.utexas.edu/vtsttools/ Transition State Tools for VASP (VTST)] Packages by Univ.Texas
: [[IDM]] Improved Dimer Method by Dr.T.Bučko (Univ.Vienna)
: [http://www.catalysis.nl/~bouke/present/ VNEB & Dimer Method] by Jónsson Group (Univ.Washington)

3. Forums / FAQs

: [http://cms.mpi.univie.ac.at/vasp-forum/forum.php Official VASP Forum]
: [http://theory.cm.utexas.edu/forum/ Forum by VTST Group]

4. Visualizers

: Direct visualization (and editing) of VASP input/output:

:: [[p4v]] / [[P4V]] = "p4vasp" ''aka'' "python4vasp" (Python-based)
:: [http://homepage.univie.ac.at/daniel.spisak/downloads.html#strender STRender] (Java3D-based)
:: [http://vaspview.sourceforge.net/ VaspView] (Motif&OpenGL/Glut-based)

: Visualization after file-conversion (using [[Scripts for VASP]] or [[UPU]])

:: [http://www.xcrysden.org XCrysDen] (TclTK&MESA-based)
:: [http://www.cmbi.ru.nl/molden/ Molden]
:: [http://www.nongnu.org/xmakemol/ XMakeMol]
:: [http://www.ks.uiuc.edu/Research/vmd/ VMD] "Visual Molecular Dynamics"
:: [http://skuld.bmsc.washington.edu/raster3d/ Raster3D] (photorealistic molecular graphics)

5. Tips & Tricks

: [http://www.fyslab.hut.fi/~job Tips by Univ.Helsinki]
: [http://cst-www.nrl.navy.mil/users/erwin/vasptips/ Tips by nrl.navy.mil]

6. 3<sup>rd</sup>-Party Commercial Software based on VASP

: [http://www.govasp.com/ GoVASP]
: [http://www.materialsdesign.com/medea/ MedeA]

== SCRIPTS ==

: [[Scripts for VASP]] - Useful scripts for VASP (by ICIQ heroes)

: [http://theory.cm.utexas.edu/vtsttools/scripts.html Scripts for the VTST package]  (NEB, DOS, CHG, conversion,... by Univ.Texas)

== TRICKS ==

: [[VdW forces]] - How to include VdW forces in a simulation (Grimme Semiempirical approach D2) 

''' OBSOLETE VASP PAGE CONTENT: '''

VASP [http://cms.mpi.univie.ac.at/vasp/vasp/vasp.html] [http://10.0.7.240/wiki/images/files/vasp/vasp.pdf] &#124; 
link to the on-line manual: [http://cms.mpi.univie.ac.at/vasp/vasp/vasp.html] &#124; 
link to the notes: [http://cms.mpi.univie.ac.at/vasp-workshop/slides/documentation.htm] &#124; 
link to the VTST packages: [http://theory.cm.utexas.edu/vtsttools/] &#124; 
link to the tools: [http://theory.cm.utexas.edu/vtsttools/scripts/] &#124; 
link to tips on VASP: [http://www.fyslab.hut.fi/~job] &#124; 
[[P4v]]: [http://cms.mpi.univie.ac.at/odubay/p4vasp_site/news.php] &#124; 
Current versions: [[VASP-Current| Current versions]] &#124; 
Useful scripts for VASP: [[Scripts for VASP]] &#124; 
EXTRADOCUMENTATION How to perform a molecular dynamics: [[Image:MD-HOWTO.pdf]]

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[[User:Dkarhanek|Dkarhanek]] 18:23, 2 June 2011 (CEST)