VASP Calculation Setup Skill

You are an expert assistant for setting up VASP (Vienna Ab initio Simulation Package) calculations. Help users generate correct input files (INCAR, POSCAR, KPOINTS, POTCAR), select optimal parameters for their calculation type, and follow best practices for accurate and efficient DFT calculations.

Overview

VASP is a plane-wave DFT code widely used in materials science and computational chemistry. This skill covers:

Input Files:

INCAR: Control parameters
POSCAR: Atomic positions and lattice
KPOINTS: k-point sampling
POTCAR: Pseudopotentials

Calculation Types:

Structure relaxation
Static calculations (single-point energy)
Band structure and DOS
Molecular dynamics
Phonons and elastic properties
Advanced: GW, hybrid functionals, DFPT

Parameter Selection:

Accuracy vs efficiency trade-offs
System-specific recommendations
Convergence testing strategies

Quick Parameter Guide

Essential INCAR Parameters

Energy Cutoff (ENCUT):

ENCUT = 520  # eV, typical for PAW potentials

Default: 1.3 × ENMAX from POTCAR
Recommendation: 1.3-1.5 × ENMAX for standard calculations
Convergence test: Test 400, 450, 500, 550, 600 eV
When to increase: Forces, stresses, elastic constants

k-Point Sampling:

# Method 1: Automatic mesh
KSPACING = 0.5  # Å⁻¹, automatic generation

# Method 2: Manual KPOINTS file
# Recommended density: 30-50 k-points per Å⁻¹

Precision (PREC):

PREC = Accurate  # High, Normal, Accurate

Low: Fast, testing only
Normal: Standard calculations
Accurate: Forces, phonons, production

Electronic Convergence (EDIFF):

EDIFF = 1E-6  # eV, energy convergence

Standard: 1E-6 eV
Tight: 1E-8 eV (forces, phonons)
Loose: 1E-4 eV (quick testing)

Input File Templates

INCAR: Control Parameters

bash

# System description
SYSTEM = Cu bulk FCC

# Electronic minimization
ENCUT = 520           # Cutoff energy (eV)
EDIFF = 1E-6          # SCF convergence (eV)
NELM = 100            # Max electronic steps
ALGO = Fast           # Algorithm: Normal, Fast, All
ISMEAR = 1            # Smearing: -5(tetra), 0(Gauss), 1(M-P)
SIGMA = 0.2           # Smearing width (eV)

# Precision
PREC = Accurate       # Precision level
LREAL = Auto          # Real-space projection

# Ionic relaxation
IBRION = 2            # 0=static, 1=RMM-DIIS, 2=CG
ISIF = 3              # 2=relax ions, 3=relax cell+ions
NSW = 100             # Max ionic steps
EDIFFG = -0.02        # Force convergence (eV/Å)

# Output
LWAVE = .FALSE.       # Write WAVECAR
LCHARG = .FALSE.      # Write CHGCAR

POSCAR: Atomic Structure

bash

Cu FCC bulk
1.0                    # Universal scaling
  3.61  0.00  0.00     # Lattice vectors
  0.00  3.61  0.00
  0.00  0.00  3.61
Cu                     # Element symbols
  4                    # Number of atoms
Direct                 # Direct (fractional) coordinates
  0.00  0.00  0.00
  0.50  0.50  0.00
  0.50  0.00  0.50
  0.00  0.50  0.50

Key Points:

Line 1: Comment (system description)
Line 2: Universal scaling factor
Lines 3-5: Lattice vectors (Å)
Line 6: Element symbols (must match POTCAR order)
Line 7: Number of atoms per element
Line 8: Coordinate type (Direct or Cartesian)
Lines 9+: Atomic positions

KPOINTS: k-Point Sampling

Gamma-Centered Mesh (most common):

bash

Automatic mesh
0                      # 0=automatic
Gamma                  # Gamma or Monkhorst-Pack
  8  8  8              # k-point grid
  0  0  0              # Shift

Monkhorst-Pack:

bash

Automatic mesh
0
Monkhorst-Pack
  8  8  8
  0  0  0

Band Structure Path:

bash

k-points for band structure
10                     # Number of points between high-symmetry points
Line-mode              # Line mode for band structure
Reciprocal
  0.0  0.0  0.0   !Γ
  0.5  0.0  0.5   !X

  0.5  0.0  0.5   !X
  0.5  0.25 0.75  !W

POTCAR: Pseudopotentials

Generation:

bash

# Concatenate POTCARs in same order as POSCAR
cat ~/vasp/potpaw_PBE/Cu/POTCAR > POTCAR

# For compounds:
cat ~/vasp/potpaw_PBE/Cu/POTCAR \
    ~/vasp/potpaw_PBE/O/POTCAR > POTCAR

Choosing POTCARs:

Standard:
```
potpaw_PBE/Element/POTCAR
```

GW calculations:

potpaw_PBE.52/Element/POTCAR

potpaw_PBE.54/

_sv: Include semicore states (more accurate, slower)
_pv: Include p as valence
_h: Harder potential (higher ENMAX)

Parameter Selection by Calculation Type

1. Structure Relaxation

INCAR:

bash

IBRION = 2            # Conjugate gradient
ISIF = 3              # Relax cell + ions
NSW = 100
EDIFFG = -0.02        # Force convergence
ISMEAR = 1            # Methfessel-Paxton
SIGMA = 0.2

Convergence Criteria:

```
EDIFFG < 0
```
: Force-based (recommended: -0.01 to -0.05 eV/Å)
```
EDIFFG > 0
```
: Energy-based (less common)

2. Static Calculation (Single-Point)

INCAR:

bash

IBRION = -1           # No ionic updates
NSW = 0
ISMEAR = -5           # Tetrahedron (accurate DOS)
# OR
ISMEAR = 0            # Gaussian (if tetra not converged)
SIGMA = 0.05

3. Band Structure

Step 1: Self-consistent calculation

bash

ICHARG = 2            # From atoms
LCHARG = .TRUE.       # Write CHGCAR

Step 2: Non-self-consistent band structure

bash

ICHARG = 11           # Read CHGCAR, no update
LORBIT = 11           # Write PROCAR
# Use line-mode KPOINTS

4. Density of States (DOS)

INCAR:

bash

ISMEAR = -5           # Tetrahedron method
LORBIT = 11           # Projected DOS
NEDOS = 3000          # DOS resolution
# Use dense k-point mesh

5. Molecular Dynamics

INCAR:

bash

IBRION = 0            # MD
NSW = 1000            # MD steps
POTIM = 1.0           # Time step (fs)
TEBEG = 300           # Start temperature (K)
TEEND = 300           # End temperature
SMASS = 0             # NVE: 0, NVT: >0
MDALGO = 2            # 1=Andersen, 2=Nose-Hoover

6. Phonons (DFPT)

INCAR:

bash

IBRION = 6            # DFPT for phonons
NFREE = 2             # Central differences
POTIM = 0.015         # Displacement (Å)
EDIFF = 1E-8          # Tight convergence!

7. Elastic Constants

INCAR:

bash

IBRION = 6            # DFPT
ISIF = 3
NFREE = 4             # For elastic constants

Advanced Parameters

Hybrid Functionals (HSE06, PBE0)

HSE06:

bash

LHFCALC = .TRUE.      # Activate hybrid
HFSCREEN = 0.2        # HSE screening parameter
AEXX = 0.25           # Exact exchange fraction
ALGO = All            # Or Damped
TIME = 0.4            # Damping for convergence

GW Calculations

Step 1: DFT (PBE)

bash

ALGO = Exact
NBANDS = 200          # Many empty bands
LOPTICS = .TRUE.

Step 2: GW

bash

ALGO = GW0  # Or EVGW
NOMEGA = 50

DFT+U (Correlated Systems)

INCAR:

bash

LDAU = .TRUE.
LDAUTYPE = 2          # Dudarev
LDAUL = 2 -1          # l quantum number (d, s/p)
LDAUU = 5.0 0.0       # U value (eV)
LDAUJ = 0.0 0.0       # J value

van der Waals Corrections

DFT-D3:

bash

IVDW = 11             # DFT-D3 (Grimme)

vdW-DF:

bash

GGA = MK              # optPBE-vdW
LUSE_VDW = .TRUE.
AGGAC = 0.0000

Convergence Testing Strategy

1. k-Point Convergence

bash

# Test sequence
KPOINTS: 4x4x4, 6x6x6, 8x8x8, 10x10x10, 12x12x12

# Converged when ΔE < 1 meV/atom between successive grids

2. Energy Cutoff Convergence

bash

# Test ENCUT
ENCUT: 400, 450, 500, 550, 600 eV

# Converged when ΔE < 1 meV/atom
# Forces may need higher cutoff

3. Systematic Approach

First: Converge ENCUT (fix k-points at moderate density)
Second: Converge k-points (use converged ENCUT)
Document: Save convergence test results

Smearing Methods (ISMEAR)

ISMEAR	Method	Use Case
-5	Tetrahedron	Static calcs, DOS, accurate energies
-4	Tetrahedron+Blöchl	Like -5, slightly different
-1	Fermi smearing	Metals
0	Gaussian	General purpose
1+	Methfessel-Paxton order N	Relaxations, metals

Recommendations:

Metals, relaxation: ISMEAR=1, SIGMA=0.2
Semiconductors, relaxation: ISMEAR=0, SIGMA=0.05
Static, DOS: ISMEAR=-5 (no SIGMA needed)
Very large systems: ISMEAR=-1, SIGMA=0.1

Common Parameter Combinations

Standard Relaxation (Metals)

bash

# INCAR
ENCUT = 520
PREC = Accurate
IBRION = 2
ISIF = 3
NSW = 100
EDIFFG = -0.02
ISMEAR = 1
SIGMA = 0.2
ALGO = Fast
LREAL = Auto

# KPOINTS
Gamma-centered
0
Gamma
  8  8  8
  0  0  0

High-Accuracy Static Calculation

bash

# INCAR
ENCUT = 600          # Higher cutoff
PREC = Accurate
IBRION = -1
NSW = 0
EDIFF = 1E-8         # Tight convergence
ISMEAR = -5          # Tetrahedron
ALGO = Normal
LREAL = .FALSE.      # Reciprocal space

# KPOINTS (very dense)
0
Gamma
  12 12 12
  0  0  0

Fast Testing Setup

bash

# INCAR
ENCUT = 400          # Lower cutoff
PREC = Normal
EDIFF = 1E-4         # Loose
ISMEAR = 0
SIGMA = 0.1
ALGO = Fast
LREAL = Auto

# KPOINTS (coarse)
0
Gamma
  4  4  4
  0  0  0

Performance Optimization

Parallelization

INCAR:

bash

NCORE = 4            # Cores per band (orbital parallelization)
# OR
NPAR = 8             # Number of groups for band parallelization
KPAR = 4             # k-point parallelization
LPLANE = .TRUE.      # Plane-wise distribution

Guidelines:

NCORE ≈ number of cores per node / 2-4
KPAR = number of k-points (or divisor)
For large systems (>100 atoms): NCORE=1-4
For many k-points: Use KPAR

Memory Management

bash

LREAL = Auto         # Reduce memory for large systems
NCORE = 4            # Reduce memory per core

Error Handling

Common Errors and Fixes

"ZBRENT: fatal error in bracketing"

bash

# Fix: Reduce POTIM or use different IBRION
POTIM = 0.2

"EDDDAV: X eigenvalues not converged"

bash

# Fix: Increase NELM, change ALGO
NELM = 200
ALGO = All

"Sub-Space-Matrix is not hermitian"

bash

# Fix: Reduce POTIM, check structure
POTIM = 0.1
SYMPREC = 1E-8

SCF not converging:

bash

# Try sequential fixes:
1. ALGO = All
2. Increase NELM = 200
3. AMIX = 0.2, BMIX = 0.0001
4. Check initial structure (too close atoms?)

Best Practices

Always Converge: Test k-points and ENCUT before production runs
Use Symmetry: Let VASP detect symmetry (speeds up calculations)
Check OUTCAR: Verify "reached required accuracy" message
Monitor: Check OSZICAR during run for convergence
Save Everything: Keep all outputs (OUTCAR, vasprun.xml) for analysis
Consistent Pseudopotentials: Use same POTCAR set for all related calculations
Document Settings: Record all INCAR parameters used

Calculation Workflows

Full Relaxation → Properties

Relaxation: Optimize structure (ISIF=3, IBRION=2)
Static: Accurate energy (ISMEAR=-5, dense k-points)
Band Structure: Non-SCF with line-mode k-points
DOS: Dense k-mesh with ISMEAR=-5
Properties: Phonons, elastic, etc.

Convergence Testing Workflow

Rough optimization: Low ENCUT, coarse k-points
Test ENCUT: Fixed k-points, vary ENCUT
Test k-points: Converged ENCUT, vary k-mesh
Production: Use converged parameters

Subskills

Invoke specific subskills for detailed guidance:

relaxation - Structure optimization workflows
electronic-structure - Band structure and DOS calculations
molecular-dynamics - MD simulations in VASP
advanced-functionals - Hybrid, GW, DFT+U methods
phonons - DFPT phonon calculations
convergence - Systematic convergence testing

Quick Decision Guide

What type of calculation?

Goal	IBRION	ISIF	ISMEAR	EDIFFG
Relax ions only	2	2	1	-0.02
Relax cell+ions	2	3	1	-0.02
Static energy	-1	2	-5	N/A
MD simulation	0	2	0	N/A
Band structure	-1	2	0	N/A
Phonons (DFPT)	6	2	0	N/A

References

VASP Manual: https://vasp.at/wiki/The_VASP_Manual
VASP Tutorials: https://vasp.at/tutorials/latest/
Parameter Index: https://vasp.at/wiki/index.php/Category:INCAR

vasp

NPX Install

Tags

SKILL.md Content

VASP Calculation Setup Skill

Overview

Quick Parameter Guide

Essential INCAR Parameters

Input File Templates

INCAR: Control Parameters

POSCAR: Atomic Structure

KPOINTS: k-Point Sampling

POTCAR: Pseudopotentials

Parameter Selection by Calculation Type

1. Structure Relaxation

2. Static Calculation (Single-Point)

3. Band Structure

4. Density of States (DOS)

5. Molecular Dynamics

6. Phonons (DFPT)

7. Elastic Constants

Advanced Parameters

Hybrid Functionals (HSE06, PBE0)

GW Calculations

DFT+U (Correlated Systems)

van der Waals Corrections

Convergence Testing Strategy

1. k-Point Convergence

2. Energy Cutoff Convergence

3. Systematic Approach

Smearing Methods (ISMEAR)

Common Parameter Combinations

Standard Relaxation (Metals)

High-Accuracy Static Calculation

Fast Testing Setup

Performance Optimization

Parallelization

Memory Management

Error Handling

Common Errors and Fixes

Best Practices

Calculation Workflows

Full Relaxation → Properties

Convergence Testing Workflow

Subskills

Quick Decision Guide

References

See Also