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here is the CIF file of CaCO3 (http://www.crystallography.net/cod/1010962.html). I have opened it using Vesta and get the following data:

Title C Ca O3
Lattice type C
Space group name Custom
Space group number 167
Setting number 1
Lattice parameters
a b c alpha beta gamma
6.36000 6.36000 6.36000 46.1000 46.1000 46.1000
Unit-cell volume = 121.856657 Å^3
Structure parameters
x y z Occ. U Site Sym.
1 Ca Ca1 0.25000 0.25000 0.25000 1.000 0.000 2 -
2 C C1 0.00000 0.00000 0.00000 1.000 0.000 2 -
3 O O1 0.25000 -0.25000 0.00000 1.000 0.000 6 -

Using the info above I have prepared the Quantum Espresso file as follows(I just point specific cards):

&SYSTEM
ibrav = 0
celldm(1) = 6.36000
/
CELL_PARAMETERS {angstrom}
6.36000 0.00000 0.00000
0.00000 6.36000 0.00000
0.00000 0.00000 6.36000
ATOMIC_POSITIONS {crystal}
Ca 0.25000 0.25000 0.25000
C 0.00000 0.00000 0.00000
O 0.25000 -0.25000 0.00000

The above info are okay? I am confused about cell_parameters how can I include alpha beta gamma angle in the QE file?

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2 Answers 2

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I exported to POSCAR from VESTA

C Ca O3
1.0
        6.3600001335         0.0000000000         0.0000000000
        4.4100358425         4.5827050490         0.0000000000
        4.4100358425         1.8764926660         4.1809043090
   Ca    C    O
    2    2    6
Direct
     0.250000000         0.250000000         0.250000000
     0.750000000         0.750000000         0.750000000
     0.000000000         0.000000000         0.000000000
     0.500000000         0.500000000         0.500000000
     0.250000000         0.750000000         0.000000000
     0.000000000         0.250000000         0.750000000
     0.750000000         0.000000000         0.250000000
     0.250000000         0.750000000         0.500000000
     0.750000000         0.500000000         0.250000000
     0.500000000         0.250000000         0.750000000

Then it is more easier to just copy paste into quantum espresso file

&SYSTEM
ibrav = 0
/
CELL_PARAMETERS {angstrom}
        6.3600001335         0.0000000000         0.0000000000
        4.4100358425         4.5827050490         0.0000000000
        4.4100358425         1.8764926660         4.180904309
ATOMIC_POSITIONS {crystal}
  Ca   0.250000000         0.250000000         0.250000000
  Ca   0.750000000         0.750000000         0.750000000
  C    0.000000000         0.000000000         0.000000000
  C    0.500000000         0.500000000         0.500000000
  O    0.250000000         0.750000000         0.000000000
  O    0.000000000         0.250000000         0.750000000
  O    0.750000000         0.000000000         0.250000000
  O    0.250000000         0.750000000         0.500000000
  O    0.750000000         0.500000000         0.250000000
  O    0.500000000         0.250000000         0.750000000

Otherwise use https://www.materialscloud.org/work/tools/qeinputgenerator

enter image description here

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1
  • $\begingroup$ Thank you so much for your help! $\endgroup$ Commented May 16 at 1:42
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Step1: Save the file as a CIF file:

Save as> Choose .cif extension.

Step2: Install cif2cell:

pip3 install cif2cell

Step3: Use cif2cell to convert CIF file into a QE input file:

cif2cell cif_filename.cif -p quantum-espresso input_file_name.in
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