VASP

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 (2nd-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.

Useful Links

Using VASP on Cirrus

VASP is only available to users who have a valid VASP licence. Only VASP 6 is available on Cirrus and requests for access need to be made via SAFE.

If you VASP 6 licence and wish to have access to VASP 6 on Cirrus please request access through SAFE:

How to request access to package groups

Once your access has been enabled, you access the VASP software using the vasp modules in your job submission script. You can see which versions of VASP are currently available on Cirrus with

module avail vasp

Once loaded, the executables are called:

vasp_std - Multiple k-point version
vasp_gam - GAMMA-point only version
vasp_ncl - Non-collinear version

All executables include:

libBEEF functionality
LibXC functionality
Wannier90 support
HDF5 support
Additional MD algorithms accessed via the MDALGO keyword.

Running parallel VASP jobs

Tip

If you are running Γ-point calculations, the vasp_gam executable typically runs around 50% faster than vasp_std.

Smaller than single node VASP jobs

When running on less than a node you omit the --exclusive flag from your job submission scripts.

The following example runs a 36-core VASP calculation on a single node on Cirrus:

#!/bin/bash

# job options (name, compute nodes, job time)
#SBATCH --job-name=VASP
#SBATCH --nodes=1
#SBATCH --tasks-per-node=36
#SBATCH --cpus-per-task=1
#SBATCH --time=0:20:0

# Replace [budget code] below with your project code (e.g. t01)
#SBATCH --account=[budget code]
# Replace [partition name] below with your partition name (e.g. standard)
#SBATCH --partition=[partition name]
# Replace [qos name] below with your qos name (e.g. standard,long)
#SBATCH --qos=[qos name]

# Load VASP version 6 module
module load vasp/6

# Set number of OpenMP threads to 1
export OMP_NUM_THREADS=1
export OMP_PLACES=cores
export SRUN_CPUS_PER_TASK=$SLURM_CPUS_PER_TASK

# Run standard VASP executable
#   --hint=nomultithread - ensures VASP uses physical cores
#   --distribution=block:block - ensure best placement of MPI tasks for 
#       collective comms performance
srun --hint=nomultithread --distribution=block:block vasp_std

Multi-node VASP jobs

VASP can exploit multiple nodes on Cirrus.

Tip

If you are running multi-node VASP jobs you will often need to use half the cores on a node or less to achieve good performance due to memory/interconnect contention from the high number of cores per node.

The following script will run a VASP job using 2 nodes with half the cores on each node (144 cores) being used for VASP MPI processes. This gives 288 cores in total for this VASP job

#!/bin/bash

# job options (name, compute nodes, job time)
#SBATCH --job-name=VASP
#SBATCH --nodes=2
#SBATCH --tasks-per-node=144
#SBATCH --cpus-per-task=2
#SBATCH --exclusive
#SBATCH --time=0:20:0

# Replace [budget code] below with your project code (e.g. t01)
#SBATCH --account=[budget code]
# Replace [partition name] below with your partition name (e.g. standard)
#SBATCH --partition=[partition name]
# Replace [qos name] below with your qos name (e.g. standard,long)
#SBATCH --qos=[qos name]

# Load VASP version 6 module
module load vasp/6

# Set number of OpenMP threads to 1
export OMP_NUM_THREADS=1
export OMP_PLACES=cores
export SRUN_CPUS_PER_TASK=$SLURM_CPUS_PER_TASK

# Run standard VASP executable
#   --hint=nomultithread - ensures VASP uses physical cores
#   --distribution=block:block - ensure best placement of MPI tasks for 
#       collective comms performance
srun --hint=nomultithread --distribution=block:block vasp_std