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Tutorial: Calculating PDOS and Fatbands with VASP and pyband

Author: Changming Ke

Introduction

This tutorial guides you through obtaining Projected Density of States (PDOS) and fatband structures using VASP and the pyband toolset. pyband provides convenient scripts (pydos and pyband) to visualize electronic structure data from VASP calculations.

Prerequisites

Part 1: Preparing VASP Calculations

1.1 Structure Preparation

Create a POSCAR file with your desired crystal structure. Ensure proper formatting with lattice parameters and atomic coordinates.

1.2 INCAR Settings for SCF Calculation to Get a CHGCAR

Use these key parameters in your INCAR file: 

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LCHARG = True
NSW = 0
ICHARG = 2
ISMEAR = 0
KPOINTS: 
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Automatic mesh
0
Gamma
3 3 3            # k-point grid density
0  0  0             # Shift

1.3.1 INCAR Settings for PDOS Calculation (NSCF)

Use these key parameters in your INCAR file:

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# Electronic structure settings
ISTART = 1          # Start from scratch
ICHARG = 11          # To obtain the eigenvalues (for band-structure plots) or the density of states (DOS) of a given charge density read from CHGCAR
LORBIT = 11         # Write orbitally resolved DOS (essential for PDOS)
ISMEAR = -5         #  Tetrahedron method
KPOINTS Settings for PDOS Calculation, more densed kpoints 

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Automatic mesh
0
Gamma
10 10 10            # k-point grid density
0  0  0             # Shift

1.3.2 INCAR Settings for Fatband Calculation (NSCF)

Use these key parameters in your INCAR file: 

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ISTART = 1          # Start from scratch
ICHARG = 11          # To obtain the eigenvalues (for band-structure plots) or the density of states (DOS) of a given charge density read from CHGCAR
LORBIT = 11         # Write orbitally resolved DOS (essential for PDOS)
ISMEAR = -5         #  Tetrahedron method
Use a k-point path through high-symmetry points for band structures:

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Line-mode
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Reciprocal
10                  # Number of k-points per segment
Gamma  0.0 0.0 0.0
M      0.5 0.5 0.0
K      0.333 0.333 0.0
Gamma  0.0 0.0 0.0

Part 2: Plotting PDOS with pydos

The pydos script visualizes partial density of states from VASP's PROCAR file.

2.1 Basic PDOS Plot

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pydos -p '1 3 4' -x -1 2 -y 0 6 -z 0.65
  • -p '1 3 4': Specifies atom indices (1-based) to include in PDOS
  • -x -1 2: Sets x-axis limits (energy range)
  • -y 0 6: Sets y-axis limits (DOS intensity)
  • -z 0.65: Sets energy reference (e.g., Fermi level)

2.2 Grouped Atom PDOS

Plot PDOS for multiple atom groups with different colors:

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pydos -p '1 3 4' -p '2 7 8' -p '5 6 9' -z 0.65 -x -1 2 -y 0 6

This command creates a PDOS plot with three distinct groups of atoms, each represented by a different color.

2.3 Saving Output

By default, pydos generates a PNG image, and save file to a .dat file. To specify a custom filename:

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pydos -p '1-4' -o my_pdos.png --tofile pdos.dat

Part 3: Plotting Fatbands with pyband

Fatband plots show the contribution of specific atoms/orbitals to electronic bands using colored dots or lines.

3.1 Basic Fatband Plot

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pyband --occ '1 3 4'
  • --occ '1 3 4': Shows contribution from atoms 1, 3, and 4
  • Dots size represents the weight of specified atoms in each band

3.2 Orbital-Projected Fatbands

Include specific orbitals using the --spd flag:

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pyband --occ '1 3 4' --spd 'd' -k mgkm
  • --spd 'd': Projects only d-orbitals (4-8 in VASP's orbital numbering)
  • -k mgkm: Labels high-symmetry k-points on the x-axis

Orbital numbering in pyband: - s orbital: 0 - p orbitals (py, pz, px): 1, 2, 3 - d orbitals (dxy, dyz, dz2, dxz, dx2): 4, 5, 6, 7, 8

3.3 Multiple Atom Groups with Colormap

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pyband --occ '1 2' --occ '3 4 5 6' --occL -t --triAxesLabels Mo S Se -k mgkm
  • --occL: Uses colormap instead of dot size
  • -t: Enables transparency
  • --triAxesLabels: Labels for each atom group

3.4 Custom Colors and Orbital Combinations

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pyband --occ '3 4' --spd '1' --occMc 'red' --occ '3-4' --spd '2-3' --occMc 'blue'
  • --spd '1': p-orbital (py) projection
  • --spd '2-3': pz and px orbitals
  • --occMc: Sets custom color for each group