Difference between revisions of "Structural and electronic properties of semiconductors and metals"
Line 23: | Line 23: | ||
a is the lattice parameter | a is the lattice parameter | ||
− | Now let's see in detail how a QE input is structured to make a total energy calculation for this system | + | Now let's see in detail how a QE input is structured to make a total energy calculation for this system. An example can be found in ~/LabQSM/LAB_1/test_diamond/scf.diamond.in that you can read e.g. using the editor <code>vi</code>: |
+ | |||
+ | &CONTROL | ||
+ | prefix='diamond', | ||
+ | calculation = 'scf' | ||
+ | restart_mode='from_scratch', | ||
+ | pseudo_dir = './pseudo/' | ||
+ | outdir = './SCRATCH' | ||
+ | / | ||
+ | &SYSTEM | ||
+ | ibrav = 2, | ||
+ | celldm(1) = 6.7402778 | ||
+ | nat = 2, | ||
+ | ntyp = 1, | ||
+ | ecutwfc = 40.0 | ||
+ | / | ||
+ | &ELECTRONS | ||
+ | mixing_mode = 'plain' | ||
+ | mixing_beta = 0.7 | ||
+ | conv_thr = 1.0d-8 | ||
+ | / | ||
+ | ATOMIC_SPECIES | ||
+ | C 12.011 C.pz-vbc.UPF | ||
+ | ATOMIC_POSITIONS (alat) | ||
+ | C 0.00 0.00 0.00 | ||
+ | C 0.25 0.25 0.25 | ||
+ | K_POINTS {automatic} | ||
+ | 4 4 4 0 0 0 |
Revision as of 13:43, 1 December 2020
Prev: LabQSM#Lecture 1: Basic DFT calculations and Convergences
Structural and electronic properties of Diamond
In this tutorial we will see how to setup a calculation and to get total energies using the PW code from the Quantum ESPRESSO distribution.
Some helpful conversions:
1 bohr = 1 a.u. (atomic unit) = 0.529177249 angstroms.
1 Rydberg = 13.6056981 eV
1 eV =1.60217733 x 10-19 Joules
For all first-principles calculations, you must pay attention to two convergence parameters. The first one is the energy cutoff, which is the max kinetic energy used in wave-function expansion. The second is the number of k-points, which measures how well the continuous integral over the BZ is discretized.
Diamond is a face-centered cubic structure with two C atoms at 0 0 0 and 0.25 0.25 0.25 a is the lattice parameter
Now let's see in detail how a QE input is structured to make a total energy calculation for this system. An example can be found in ~/LabQSM/LAB_1/test_diamond/scf.diamond.in that you can read e.g. using the editor vi
:
&CONTROL prefix='diamond', calculation = 'scf' restart_mode='from_scratch', pseudo_dir = './pseudo/' outdir = './SCRATCH' / &SYSTEM ibrav = 2, celldm(1) = 6.7402778 nat = 2, ntyp = 1, ecutwfc = 40.0 / &ELECTRONS mixing_mode = 'plain' mixing_beta = 0.7 conv_thr = 1.0d-8 / ATOMIC_SPECIES C 12.011 C.pz-vbc.UPF ATOMIC_POSITIONS (alat) C 0.00 0.00 0.00 C 0.25 0.25 0.25 K_POINTS {automatic} 4 4 4 0 0 0