[QE-users] Trouble reading Atomic Positions from CIF file

[Pietro Davide Delugas]

Dear Aziz

you can use the CIF file coordinates directly   using the crystal_sg 
format for the coordinates in atomic positions, and specify the 
space_group number in the system namelist ( please look at the input 
documentation ).

This information is all contained in the CIF file. You were also using 
the wrong ibrav,
if you look at the  axes angles you can see that A and B axes are 
orthogonal to C axis and they form a 120 angle between them so I guess 
should be ibrav=4 not 5.

Other thing for the CIF files includes 3 coordinates even for the 3a 
positions, 2 of them are redundant and I don't know why the programs 
stops instead of ignoring them so you have to take them off the input.

You can find more information about any wyckoff position in this site

http://www.cryst.ehu.es/cryst/get_wp.html

I attach an input file with Wyckoff position for your case, I hope it works

regards - Pietro


On 10/30/2018 09:30 PM, Aziz Fall wrote:
> Dear Quantum Espresso team,
>
> I am a researcher from the University of Michigan Ann Arbor. I am 
> still fairly new to Quantum Espresso. I have been recently trying to 
> run a band structure calculation of CrI3. The first step I took was to 
> write the scf input file for CrI3 and plug in all of the cell 
> parameters and atomic positions from a corresponding CIF file that I 
> downloaded from Springer. But when I visualize the scf file in 
> XCrysden it gives me the wrong atomic structure, even though the 
> atomic positions I put into it are from the cif file. Any help in 
> solving this problem would be greatly appreciated. I have attached 
> both my scf and cif files below.
>
>
> Thank You,
> Sincerely Aziz Fall
>
>
> _______________________________________________
> users mailing list
> users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users


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&control 
	calculation='relax'
	restart_mode='from_scratch',
	prefix='crI3'
	pseudo_dir='/scratch/pdelugas/qe_gitlab/pseudo/',
	outdir='./',
/
&system
        space_group = 151
	ibrav = 4,  
	A = 6.85, 
	B = 6.85 , 
	C = 19.89 ,
	nat= 5, ntyp= 2,
	ecutwfc =  16.7,
	lspinorb=.true.,
	noncolin = .true.,
	rhombohedral=.false.,
	occupations = 'smearing', smearing='gaussian', degauss=0.01 
/
&electrons
	mixing_beta = 0.7
	conv_thr = 1.0d-6
/
&ions 
	ion_dynamics="bfgs", 
/
ATOMIC_SPECIES 
Cr 52.00 Cr.rel-pbe-spn-rrkjus_psl.1.0.0.UPF
I 126.90 I.rel-pbe-n-rrkjus_psl.0.2.2.UPF
ATOMIC_POSITIONS crystal_sg  
Cr      3a   0.44444
Cr      3a   0.77778
I       6c   0.11111 0.22222 0.406                 
I       6c   0.11111 0.55556 0.26                  
I       6c   0.44445 0.22222 0.26                  
K_POINTS (automatic)
8 8 1 0 0 0