exercises:2016_ethz_mmm:bs
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exercises:2016_ethz_mmm:bs [2016/05/24 13:37] – pshinde | exercises:2016_ethz_mmm:bs [2016/05/27 14:36] – dpasserone | ||
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===== 1. Running an SCF job and calculating the band structure and DOS of graphene ===== | ===== 1. Running an SCF job and calculating the band structure and DOS of graphene ===== | ||
- | Here we give some notes on how to use [[http:// | + | Here we give some notes on how to use [[http:// |
Steps: | Steps: | ||
1. Before starting the calculations please load following modules. Please type the commands at the terminal. | 1. Before starting the calculations please load following modules. Please type the commands at the terminal. | ||
- | $ module load intel/12.1.2 | + | $ module load intel/14.0.1 open_mpi/1.6.5 |
- | $ module load open_mpi/1.4.5 | + | $ module load quantum_espresso |
- | $ module load espresso/ | + | |
- | 2. Create a new directory and download | + | 2. Download |
+ | <note important> | ||
**Self-Consistent Field (SCF) calculation: | **Self-Consistent Field (SCF) calculation: | ||
- | The SCF calculation means that the program iteratively updates the orbitals | + | The SCF calculation means that the program iteratively updates the orbitals |
- | ibrav = 4 ! definition of the crystal system (hexagonal for graphene) | + | ibrav = 4 ! definition of the crystal system (hexagonal for graphene |
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KX KY KZ 0 0 0 | KX KY KZ 0 0 0 | ||
- | 3. Insert the Γ-centred k-grid KX KY KZ (e.g. 10 10 1). As we are dealing with two-dimensional (2D) system (and so 2D BZ), KZ should be 1. There are two choices for the centre of the mesh: 1) centred on Γ (Γ belongs to the mesh) and 2) centred around Γ (Γ does not belong to the mesh). The second choice can break the symmetry!!. Here we used Γ centred k-grid. | + | 3. Insert the Γ-centred k-grid KX KY KZ (e.g. 10 10 1). As we are dealing with two-dimensional (2D) system (and so 2D BZ), KZ should be 1. There are two choices for the centre of the mesh: 1) centred on Γ (Γ belongs to the mesh) and 2) centred around Γ (Γ does not belong to the mesh). The second choice can break the symmetry!!. Here we use Γ centred k-grid. |
4. Run the ground-state calculation using pw.x code of the QUANTUM ESPRESSO suit, | 4. Run the ground-state calculation using pw.x code of the QUANTUM ESPRESSO suit, | ||
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$ grep “Fermi energy” | $ grep “Fermi energy” | ||
- | 6. Copy the mol.save directory to scf-mol.save. The scf-mol.save is required for ' | + | 6. Copy the mol.save directory to scf-mol.save. The scf-mol.save is required for the ' |
$ cp -rf mol.save/ scf-mol.save/ | $ cp -rf mol.save/ scf-mol.save/ | ||
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8. and then use dos.in input file to get the density of states from -20 to 10 eV. | 8. and then use dos.in input file to get the density of states from -20 to 10 eV. | ||
$ bsub -n 4 " mpirun dos.x < dos.in > DOS.out " | $ bsub -n 4 " mpirun dos.x < dos.in > DOS.out " | ||
- | First column of " | + | First column of " |
{{ graphene_dos.png? | {{ graphene_dos.png? | ||
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{{ Graphene-BZ.png? | {{ Graphene-BZ.png? | ||
- | $ gcc –Wall kpoints.c | + | $ gcc -Wall kpoints.c |
and then | and then | ||
$ ./kpoints | $ ./kpoints | ||
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- Repeat steps 3-11 for different k-grids (10 10 1, 20 20 1, 30 30 1 and 40 40 1) and plot the band structures and DOS. | - Repeat steps 3-11 for different k-grids (10 10 1, 20 20 1, 30 30 1 and 40 40 1) and plot the band structures and DOS. | ||
- What changes do you see in the band structure and DOS? Why? | - What changes do you see in the band structure and DOS? Why? | ||
+ | - Repeat the exercise with a larger unit cell and a smaller number of k points. To this end you can use the provided script ** copy_crystal ** in the following way: | ||
+ | - copy the crystal coordinates in a file crys.in, then run ./ | ||
</ | </ | ||
- | Don't forget to visit [[http:// | + | Don't forget to visit [[http:// |
exercises/2016_ethz_mmm/bs.txt · Last modified: 2020/08/21 10:15 by 127.0.0.1