*Note: This tutorial is for beginners only.

In the previous chapter, we have completed the structure optimization of diamond and obtained the optimized diamond crystal structure using the PBE functional. In this section, we will complete the calculation of diamond band and electron state density.

>> Create a new folder (name: scf) and perpar four input files and script for submitting task under it

  • INCAR:

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    System = SCF
    PREC = N
    ISTART = 0
    ICHARG =2
    ENCUT = 520
    EDIFF  = 1e-5
    EDIFFG = -0.001
    IBRION = -1
    ISMEAR = 0
    SIGMA = 0.05
    LCHARG = T
    LWAVE  = T
    NPAR = 4

  • KPOINTS (Please make sure that k points are dense enough!):

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    K-Mesh
    0
    Monkhorst-Pack
      11 11 11
    0.0  0.0  0.0

  • POTCAR:
    Copy it directly from the folder. The head of POTCAR of C:
    PBE functional of Carbon

  • POSCAR:
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    Diamond_Primitive Cell
    1.0
            2.5268502235         0.0000000000         0.0000000000
            1.2634251118         2.1883164851         0.0000000000
            1.2634251118         0.7294388284         2.0631645680
        C
        2
    Direct
         0.500000000         0.500000000         0.500000000
         0.750000000         0.750000000         0.750000000

Diamond Primitive Cell

  • Script for VASP run (name:job.sh):
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    #!/bin/bash
    # yhcontrol show job

    yhrun -N 1 -n 24 -p work  vasp_std > vasp.log 2>&1

>> Submit the task:

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yhbatch   -N 1  -p work   ./job.sh
  • When the calculation is complete, check the log file to make sure the wave function has been written：
    vasp.log file after scf calculation

>> Create a new folder for calculating band structure of diamond：

  • mkdir band & cd band & cp ../* ./, then change the parameters of the INCAR file, e.g.:

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    System = Band
    PREC = N
    ISTART = 1  ##
    ICHARG = 11  ##
    ENCUT  = 520
    EDIFF  = 1e-5
    EDIFFG = -0.001
    IBRION = -1
    ISMEAR = 0
    SIGMA  = 0.05
    LCHARG = F  ##
    LWAVE  = F  ##
    NPAR   = 4

  • Create a KPOINGTS (brillouin zone path) file for calculating band structure of diamond. Here, I strongly recommend using the Materials Cloud platform to complete the k point path. Or you can manually set up the k-point file based on this Paper.
    Suggested High-symmetry point path in materials cloud
    In diamond case, we chose the k point path according to the materials cloud. e.g. (file name: KPOINTS):

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    K-Points
       20
    Line-Mode
    Reciprocal
      0.00000000  0.00000000  0.00000000     ! G
      0.50000000  0.00000000  0.50000000     ! X

      0.50000000  0.00000000  0.50000000     ! X
      0.62500000  0.25000000  0.62500000     ! U

      0.62500000  0.25000000  0.62500000     ! U
      0.37500000  0.37500000  0.75000000     ! K

      0.37500000  0.37500000  0.75000000     ! K 
      0.00000000  0.00000000  0.00000000     ! G

      0.00000000  0.00000000  0.00000000     ! G
      0.50000000  0.50000000  0.50000000     ! L

      0.50000000  0.50000000  0.50000000     ! L
      0.50000000  0.25000000  0.75000000     ! W

      0.50000000  0.25000000  0.75000000     ! W
      0.00000000  0.00000000  0.00000000     ! X

>> Submit the task:

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yhbatch   -N 1  -p work   ./job.sh
  • When the calculation is complete, check the log file to make sure the wave function has been written：
    vasp.log file after band strcuture calculation

>> Plot the band structure using P4VASP:

  • Download the vasprun.xml file from the cluster and import this into the P4VASP program:
  • Click electronic -> DOS+bands
  • Click Show -> Bands
  • You will see:
  • Export .dat file: Click Graph -> Export
  • Drag the .dat file into the Origin:
  • Comparison with Materials Project database

>> Create a new folder for calculating density of states of diamond：

  • In scf folder, creat dos a folder: mkdir dos, and copy all files in scf folder into dos folder: cp ./* ./dos/. Then, go to dos folder: cd ./dos/

  • Change the parameters of the INCAR file, e.g.:

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    System = DOS
    PREC = N
    ISTART = 1  
    ICHARG = 11  
    ENCUT  = 520
    EDIFF  = 1e-5
    EDIFFG = -0.001
    IBRION = -1
    ISMEAR = -5.  ##
    # SIGMA  = 0.05
    LCHARG = F   
    LWAVE  = F   
    NPAR   = 4
    NEDOS = 2000
    LORBIT = 11 # or 10 for per atom

  • Change the KPOINTS file, It’s denser than scf calculation, e.g.:

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    K-Mesh
    0
    Monkhorst-Pack
      25 25 25
    0.0  0.0  0.0

>> Submit the task:

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yhbatch   -N 1  -p work   ./job.sh

  • When the calculation is complete, check the log file：
    vasp.log file after dos strcuture calculation

  • Plot the pdos using P4VASP：

Actually, there are many ways to plot the results, and the best way to do that is to use the shell or python script to extract the data, but using the official P4VSP program is a good choice for beginners.

5. Homework

References

[1] https://www.materialsproject.org
[2] https://www.materialscloud.org
[3] http://www.p4vasp.at