exercises:2016_ethz_mmm:bs
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exercises:2016_ethz_mmm:bs [2016/05/24 14:03] – pshinde | exercises:2016_ethz_mmm:bs [2020/08/21 10:15] (current) – external edit 127.0.0.1 | ||
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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. Download all the **commented** files from the media manager: {{exercise_11.2.tar.gz|}}. | + | 2. Download all the **commented** files from the media manager: {{exercise-12.tar.gz|}} |
+ | <note important> | ||
**Self-Consistent Field (SCF) calculation: | **Self-Consistent Field (SCF) calculation: | ||
- | The SCF calculation means that the program iteratively updates the orbitals until certain criterion is reached. Inspect the input file “scf.in” for graphene. The most important input parameters in scf.in are: definition of a crystal system, lattice constant, k-grid, and vacuum region to avoid interactions between two graphene sheets. In our case, a vacuum along the transverse and perpendicular | + | The SCF calculation means that the program iteratively updates the orbitals until certain criterion is reached. Inspect the input file “scf.in” for graphene. The most important input parameters in scf.in are: definition of a crystal system, lattice constant, k-grid, and vacuum region to avoid interactions between two graphene sheets. In our case, a vacuum along the perpendicular |
- | 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.1464098619.txt.gz · Last modified: 2020/08/21 10:15 (external edit)