exercise 02 :: Self-consistent field DFT calculations of Aluminium

Aliminium has 13 electrons. Its crystalline form is cubic face-centered with space group Fm-3m (number 225) with one atom in unit cell in Wyckhoff position 4a, see Bilbao Crystallographic Server. Lattice constant is 4.0495 A.

TASK 01

Construct structure of Al crystal in VESTA program (video tutorial is here). Compare with Al_cubic_SG225.vesta on webdisk.

TASK 02

Create the input file for the self-consistent field (SCF) calculations within Quantum Espresso pw.x program. For input variables refer to Input File Description.

  1. Save the following input file with the name pw-scf_Al.in, or download it from webdisk

     &control
     calculation = 'scf'
     restart_mode = 'from_scratch',
     pseudo_dir = './',
     outdir = './tmp',
     prefix = 'al'
 /
 &system
     ibrav = 2, celldm(1) = 7.652446, nat = 1, ntyp = 1, 
     ecutwfc = 15.0, occupations = 'smearing',
     smearing = 'marzari-vanderbilt', degauss = 0.05
 /
 &electrons
     diagonalization = 'david'
     mixing_beta = 0.7
     conv_thr = 1.D-6
 /
 ATOMIC_SPECIES
     Al  26.98 Al.pz-vbc.UPF
 ATOMIC_POSITIONS
     Al 0.00 0.00 0.00
 K_POINTS (automatic)
     8 8 8  0 0 0

  2. Visualize the pw-scf_Al.in input file with the XCrySDen program, e.g., using command line xcrysden --pwi pw-scf_Al.in.

  3. Download the pseudopotential file Al.pz-vbc.UPF with LDA approximation to exchange-correlation functional.

  4. Run the SCF calculations pw.x -i pw-scf_Al.in > pw-scf_Al.out

  5. Analyze the output file pw-scf_Al.out and seek for the total energy and contributions to the exchange-correlation, Hartree, and single electron energies. What is the Fermi energy?

  6. How many valence electrons were used in the calculation?

Martin Gmitra :: martin.gmitra@upjs.sk
Creative Commons License This work is licensed under a Creative Commons Attribution 4.0 International License.