MOPDOS_from_VASP

This repository contains a fortran code which computes the molecular orbital projected density of states (MOPDOS) based on VASP calculations (WAVECAR-files). The MOPDOS is calculated by projecting the Kohn-Sham orbitals of a "full" system onto the Kohn-Sham orbitals of a fragment of the full system, the "molecular" system. A detailed defintion of the MOPDOS can be found in the following publication:

[1] D. Lüftner, P. Hurdax, G. Koller, M. G. Ramsey, S. Weiß, X. Yang, S. Soubatch, F.S. Tautz, V. Feyer, A. Gottwald and P. Puschnig, Understanding the photoemission distribution of strongly interacting two-dimensional overlayers, Phys. Rev. B 96, 125402 (2017). https://doi.org/10.1103/PhysRevB.96.125402

Please cite publication [1] when using results from this code in your publications.

Authors

• Peter Puschnig (peter.puschnig@uni-graz.at)
• Daniel Lüftner (daniel.lueftner@hotmail.com)

Quick-Start

Compilation of program:

cd src
gfortran mopdos_spinpol.f90
mv a.out ../bin/mopdos_spinpol.x

Usage:

cd ../example/
../bin/mopdos_spinpol.x

The program runs for less than a second for this example data (benzene adsorbed on graphene) and produces the text outputfile MOPDOS.out containing the MOPDOS data and the log-file MOPDOS.log. Compare your output with the sample outputfile provided in the example/output/ folder which also contains the file MOPDOS.png displaying the data containd in MOPDOS.out as well as the python script plot_mopdos.py which reads in the data from MOPDOS.out and creates the plot MOPDOS.png.

Example-data

VASP data

The example/VASP folder contains the results of two VASP caclulations. The subfolder full contains the VASP calculation for the full system, here, it is a benzene ring adsorbed on a graphene layer. The subfolder molecule contains the VASP calculation for the molecular system, here, it is the benzene ring. Note that it is absolutely necessary that the unit cell dimensions and the plane wave cut-off must be identical in the full and molecular system. Also, the atomic coordintes of the molecular fragment in 'molecule' and 'full' must be identical-

Computation of the MOPDOS

In order to compute the MOPDOS go to the respective folder,

cd ../example

If necessary, edit the text file MOPDOS.in which provides the input data for running the MOPDOS program:

"VASP/full/WAVECAR"         ! name of WAVECAR file of full calculation
"VASP/molecule/WAVECAR"     ! name of WAVECAR file of molecule calculation
4                           ! number of k-points in IBZKPT
11 15                       ! band range for analysis in molecule 
1 82                        ! band range for analysis in full system
-1.5894                     ! Fermi-level of full system (energy of HOMO) in eV
0.1                         ! sigma value for Gauss broadening in MOPDOS curves
-15.0    5.00    0.02       ! range of energies for analysis (1 - 2) and energy step (3) [eV]  

Make sure that the VASP output file IBZKPT is also located in the same folder as the MOPDOS.in. Execute the program

../bin/mopdos_spinpol.x   

The resulting text output file MOPDOS.out contains the computed MOPDOS curves. You can use the python script plot_mopdos.py to read in and plot the MOPDOS curves.

Generating VASP files for your own systems

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September 6th, 2021