# VASP (Vienna Ab initio Simulation Package)¶

Information regarding the Vienna Ab initio Simulation Package (VASP) installed on Stallo.

## General information¶

### 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.

There are various type plug ins and added functionality to VASP. On Stallo, we have added support for the Texas transition state tools (vTST), the VASPsol implicit solvation model made by Hennig and Mathew from University of Florida and the Bayesian Error Estimation Functionals from the SUNCAT center, Standford.

### Online information from vendor¶

The Vasp program is not distributed via site licences. However, HPC-staff in NOTUR have access to the VASP code to be able to support any research groups that have a valid VASP license.

VASP is a commercial software package that requires a license for all who wants to run on Stallo. To get access you would need to prove that the group you are a member of holds a valid licence; a representative for the research group needs to contact Dr. Doris Vogtenhuber (doris.vogtenhuber@univie.ac.at) from the VASP team and ask for an aknowledgement of you connection to the license. A VASP representative will send this acknowledgement to us. Then your name is put into the VASP group, granting you access to the VASP 5 release of VASP on Stallo.

The support people in NOTUR, do not provide trouble shooting guides anymore, due to a national agreement that it is better for the community as a whole to add to the community info/knowledge pool where such is made available. Also, HPC staff from UiT does not provide any support to VASP 4 anymore, basically due to age of the code.

### Citation¶

When publishing results obtained with the referred software referred, please do check the developers web page in order to find the correct citation(s).

## Usage¶

You load the application by typing:

$module load VASP  This command will give you the default version. For more information on available versions, type: $ module avail VASP


Experiencewise, VASP is a rather memory intensive code. Users are advised to read up on the general job script example(s) for SLURM and Stallo, and also how to specify memory in SLURM.