[QE-users] QE-input file clarification

[Jodan Ebaya]

Good day!

I am Jordan Lee Ebaya, a second MS-PHYSICS students of Mindanao State
University Iligan Institute of Technology, Iligan CIty, Philippines.
Currenlty i am working with my graduate research which Focus on DFT
calculation using Qunatum Espresso.

I just want to ask if my input files in QE is wrong since i already have
done several trials and still i did not get the result i wanted. Base on
the journal Iread that was publish on RSC, thier calcualtion shows that
there is a 0.3eV bandgap of the Magnesium Dicarbide using Amsterdam Desnity
Functional Simulation Package ADF-BANDS with Slater Type Orbital, Double
Zeta Polarized Basis set. I also want to know, what are the cons and pros
of using differenet basis sets?

Attached documents are my relax, scf, nscf(bands) input file and the
resulted bands strutre.

Thank you and hoping for an answer for this inquery, this will be a great
help for my thesis.

Sincerely,

Jordan Lee P. Ebaya
*MS-PHYSICS Students*

Title: notepad

&control
  calculation = 'relax',
  prefix = 'MgC2_rlx',
  outdir = './tmp/',
  pseudo_dir = './pseudo/',
  verbosity = 'high',
  etot_conv_thr = 1.0d-5,
  forc_conv_thr = 1.0d-4,
/
&system
  ibrav = 0,
  nat = 3,
  ntyp = 2,
  ecutwfc = 120,
  ecutrho = 1200,
  input_dft = 'PBE',
  occupations = 'fixed',
  vdw_corr = 'grimme-d3',
/
&electrons
  conv_thr = 1.0d-8,
  mixing_beta = 0.3,
/
&ions
  ion_dynamics = 'bfgs',
/
ATOMIC_SPECIES
Mg  24.30500  Mg.pbe-spnl-kjpaw_psl.1.0.0.UPF
C   12.01100  C.pbe-n-kjpaw_psl.1.0.0.UPF

ATOMIC_POSITIONS {crystal}
  Mg  0.000000  0.000000  0.46350
  C   0.333333  0.666667  0.53650
  C   0.666667  0.333333  0.53650


CELL_PARAMETERS {angstrom}
  3.181000   0.000000   0.000000
-1.590500   2.758000   0.000000
  0.000000   0.000000  20.000000

K_POINTS automatic
  15 15 1  0 0 0

Title: notepad

&control
  calculation = 'nscf',
  prefix = 'MgC2',
  outdir = './tmp/',
  pseudo_dir = './pseudo/',
/
&system
  ibrav = 0,
  nat = 3,
  ntyp = 2,
  nbnd = 20,
  ecutwfc = 120,
  ecutrho = 1200,
  input_dft = 'PBE',
  occupations = 'fixed',
/
&electrons
  conv_thr = 1.0d-8,
/
ATOMIC_SPECIES
Mg  24.30500  Mg.pbe-spnl-kjpaw_psl.0.3.0.UPF
C   12.01100  C.pbe-n-kjpaw_psl.1.0.0.UPF

ATOMIC_POSITIONS {crystal}
Mg   0.000000000   0.000000000   0.440789640
C    0.332488607   0.664978213   0.547855180
C    0.667511393   0.335021787   0.547855180

CELL_PARAMETERS {angstrom}
  3.181000   0.000000   0.000000
-1.590500   2.758000   0.000000
  0.000000   0.000000  20.000000

K_POINTS crystal_b
  4
  0.00000 0.00000 0.00000  40   ! Gamma
  0.50000 0.00000 0.00000  40   ! M
  0.33372 0.33314 0.00000  40   ! K
  0.00000 0.00000 0.00000  0    ! Gamma

Title: notepad

&control
  calculation = 'scf',
  prefix = 'MgC2',
  outdir = './tmp/',
  pseudo_dir = './pseudo/',
  tprnfor = .true.,
  tstress = .true.,
/
&system
  ibrav = 0,
  nat = 3,
  ntyp = 2,
  ecutwfc = 120,       ! Plane-wave cutoff
  ecutrho = 1200,      ! Charge density cutoff
  input_dft = 'PBE',
  occupations = 'smearing',
  smearing = 'marzari-vanderbilt',
  degauss = 0.01,       ! Small smearing for metallic/zero-gap
  vdw_corr = 'grimme-d3',
/
&electrons
  conv_thr = 1.0d-8,
  mixing_beta = 0.3,
/
ATOMIC_SPECIES
Mg  24.305  Mg.pbe-spnl-kjpaw_psl.1.0.0.UPF
C   12.011  C.pbe-n-kjpaw_psl.1.0.0.UPF

# Relaxed atomic positions (fractional)
ATOMIC_POSITIONS {crystal}
Mg   0.000000000   0.000000000   0.440789640
C    0.332488607   0.664978213   0.547855180
C    0.667511393   0.335021787   0.547855180

# Large vacuum along z for 2D
CELL_PARAMETERS {angstrom}
  3.181000   0.000000   0.000000
-1.590500   2.758000   0.000000
  0.000000   0.000000  20.000000

K_POINTS automatic
  15 15 1 0 0 0

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