Bands with Quantum Espresso

The c2x logo is the π bond in ethene. Here we reproduce it using Quantum Espresso's PWscf. (c2x version 2.30 or later is required for this example.)

ethene.in
&CONTROL
  calculation = 'scf',
  outdir = '.',
  pseudo_dir = '.'
/
&SYSTEM
  ibrav = 0,
  nat   = 6,
  ntyp  = 2,
  ecutwfc = 35
/
&ELECTRONS
/

CELL_PARAMETERS angstrom
  8.0000000   0.0000000   0.0000000
  0.0000000   8.0000000   0.0000000
  0.0000000   0.0000000   7.0000000

ATOMIC_SPECIES
  C    1.0   C.UPF
  H    1.0   H.UPF

ATOMIC_POSITIONS angstrom
  C   4.698560000  4.000000000  3.500000000
  C   3.301440000  4.000000000  3.500000000
  H   5.270880000  4.923920000  3.500000000
  H   2.729120000  3.076080000  3.500000000
  H   2.729120000  4.923920000  3.500000000
  H   5.270880000  3.076080000  3.500000000

K_POINTS crystal
  1
  0.250000000   0.250000000   0.250000000      1.000000000

And suitable pseudopotentials were obtained with

$ curl -o C.UPF https://www.quantum-espresso.org/upf_files/C.pz-rrkjus.UPF
$ curl -o H.UPF https://www.quantum-espresso.org/upf_files/H.pz-rrkjus.UPF

Then PWscf can be run as

  $ pw.x -in ethene.in > ethene.log

Then this example becomes the same as the corresponding Castep example, save that ethene.check should be replaced by pwscf.xml. C2x will combine data from the XML file with that in pwscf.save/wfc1.dat.