[Pw_forum] General quenstion about metallic supercell

Afshin Arjangmehr ms.arjangmehr at gmail.com
Mon Feb 13 16:58:17 CET 2017


Dear all,

I have a question regarding constructing supercells in QE and performing
vc-relax. Based on recommendations available on pwscf website, I used
xcrysden to generate a rather large cell (consisting 125 atoms of
vanadium, available in attached file). But, when I modify my input script
and again visualize the structure, "translational asymmetric cell" view
shows a very strange configuration of atoms. Also, performing vc-relax
takes incredibly long time (about 6 days on 64-cores).
Is there something wrong with my method? Is this a correct super cell?
I use QE5.4.0 compiled with ifort.
---------------------------------------------------------------------------------------------------------------------
Method:

1- Constructing a simple bcc unit cell (~ in1.txt)
2- Visualizing using xcrysden, changing to primitive cell mode, repeating
cell in x,y and z-direction (5x5x5) and saving configuration (~ data.xyz)
3- Extracting atomic positions from saved configuration and modifying the
input script (in2.txt)

Thank you very much for your response.

-- 
With Best Regards
Afshin Arjhangemehr
PhD candidate in Radiation Application
Shahid Beheshti University G.C, Tehran, IRAN
(+98) 912 439 20 64
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 &CONTROL
                 calculation = 'scf' ,
                restart_mode = 'from_scratch' ,

                etot_conv_thr = 1.0E-8  ,
               forc_conv_thr = 1.0D-8 ,
               outdir='/home/koma/software/QE-USER/Output',
               pseudo_dir = '/home/koma/software/QE-USER/Pseudo-potential',
                tprnfor   = .true.
                tstress = .true.
   /
    &SYSTEM
                        ibrav = 3,
                        celldm(1) = 5.62586,
                        nat = 1,
                        ntyp = 1,
                        ecutwfc = 100
                        occupations = 'smearing' ,
                        degauss= 0.01 ,
                        smearing= 'gaussian',
                        nspin=2 ,
                        starting_magnetization(1) = 0.2 ,
 /
&ELECTRONS
                  conv_thr = 1.D-8 ,
 /
&IONS
                  ion_dynamics= 'bfgs',
                  upscale  = 70.d0,
                  pot_extrapolation = 'atomic',
                  wfc_extrapolation = 'none' ,
/
ATOMIC_SPECIES
V    50.6941    V.pbe-spn-kjpaw_psl.0.2.3.UPF
ATOMIC_POSITIONS (angstrom)
   V     0               0              0 
K_POINTS {automatic}
16 16 16 0 0 0  
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 &CONTROL
                calculation = 'vc-relax' ,
                restart_mode = 'from_scratch' ,
		prefix = 'V_125atoms' ,
                etot_conv_thr = 1.0E-2  ,
                forc_conv_thr = 1.0D-2 ,
                outdir='/share/users/mahdiani/espresso/Output',
                pseudo_dir = '/share/users/mahdiani/espresso/PS',
                tprnfor   = .true.
                tstress = .true.
 /
    &SYSTEM
                        ibrav = 3,
                        celldm(1) = 28.6293 ,
                        nat = 125,
                        ntyp = 1,
                        ecutwfc = 47 ,
                        occupations = 'smearing' ,
                        degauss= 0.05 ,
                        smearing= 'gaussian',
                        nspin=2 ,
                        starting_magnetization(1) = 0.05 ,
 /
&ELECTRONS
                  conv_thr = 1.D-2 ,
 /
&IONS
                  ion_dynamics= 'bfgs',
                  upscale  = 70.d0,
                  pot_extrapolation = 'atomic',
                  wfc_extrapolation = 'none' ,
 /
&CELL
   cell_dynamics = 'bfgs' ,
   cell_factor = 2 ,
 /
ATOMIC_SPECIES
V    50.6941    V.pbe-spn-kjpaw_psl.0.2.3.UPF
ATOMIC_POSITIONS (angstrom)
   V    0.0000000000    0.0000000000    0.0000000000
   V   -1.5149967090   -1.5149967090    1.5149967090
   V   -3.0299934180   -3.0299934180    3.0299934180
   V   -4.5449901270   -4.5449901270    4.5449901270
   V   -6.0599868360   -6.0599868360    6.0599868360
   V   -1.5149967090    1.5149967090    1.5149967090
   V   -3.0299934180    0.0000000000    3.0299934180
   V   -4.5449901270   -1.5149967090    4.5449901270
   V   -6.0599868360   -3.0299934180    6.0599868360
   V   -7.5749835450   -4.5449901270    7.5749835450
   V   -3.0299934180    3.0299934180    3.0299934180
   V   -4.5449901270    1.5149967090    4.5449901270
   V   -6.0599868360    0.0000000000    6.0599868360
   V   -7.5749835450   -1.5149967090    7.5749835450
   V   -9.0899802540   -3.0299934180    9.0899802540
   V   -4.5449901270    4.5449901270    4.5449901270
   V   -6.0599868360    3.0299934180    6.0599868360
   V   -7.5749835450    1.5149967090    7.5749835450
   V   -9.0899802540    0.0000000000    9.0899802540
   V  -10.6049769630   -1.5149967090   10.6049769630
   V   -6.0599868360    6.0599868360    6.0599868360
   V   -7.5749835450    4.5449901270    7.5749835450
   V   -9.0899802540    3.0299934180    9.0899802540
   V  -10.6049769630    1.5149967090   10.6049769630
   V  -12.1199736720    0.0000000000   12.1199736720
   V    1.5149967090    1.5149967090    1.5149967090
   V    0.0000000000    0.0000000000    3.0299934180
   V   -1.5149967090   -1.5149967090    4.5449901270
   V   -3.0299934180   -3.0299934180    6.0599868360
   V   -4.5449901270   -4.5449901270    7.5749835450
   V    0.0000000000    3.0299934180    3.0299934180
   V   -1.5149967090    1.5149967090    4.5449901270
   V   -3.0299934180    0.0000000000    6.0599868360
   V   -4.5449901270   -1.5149967090    7.5749835450
   V   -6.0599868360   -3.0299934180    9.0899802540
   V   -1.5149967090    4.5449901270    4.5449901270
   V   -3.0299934180    3.0299934180    6.0599868360
   V   -4.5449901270    1.5149967090    7.5749835450
   V   -6.0599868360    0.0000000000    9.0899802540
   V   -7.5749835450   -1.5149967090   10.6049769630
   V   -3.0299934180    6.0599868360    6.0599868360
   V   -4.5449901270    4.5449901270    7.5749835450
   V   -6.0599868360    3.0299934180    9.0899802540
   V   -7.5749835450    1.5149967090   10.6049769630
   V   -9.0899802540    0.0000000000   12.1199736720
   V   -4.5449901270    7.5749835450    7.5749835450
   V   -6.0599868360    6.0599868360    9.0899802540
   V   -7.5749835450    4.5449901270   10.6049769630
   V   -9.0899802540    3.0299934180   12.1199736720
   V  -10.6049769630    1.5149967090   13.6349703810
   V    3.0299934180    3.0299934180    3.0299934180
   V    1.5149967090    1.5149967090    4.5449901270
   V    0.0000000000    0.0000000000    6.0599868360
   V   -1.5149967090   -1.5149967090    7.5749835450
   V   -3.0299934180   -3.0299934180    9.0899802540
   V    1.5149967090    4.5449901270    4.5449901270
   V    0.0000000000    3.0299934180    6.0599868360
   V   -1.5149967090    1.5149967090    7.5749835450
   V   -3.0299934180    0.0000000000    9.0899802540
   V   -4.5449901270   -1.5149967090   10.6049769630
   V    0.0000000000    6.0599868360    6.0599868360
   V   -1.5149967090    4.5449901270    7.5749835450
   V   -3.0299934180    3.0299934180    9.0899802540
   V   -4.5449901270    1.5149967090   10.6049769630
   V   -6.0599868360    0.0000000000   12.1199736720
   V   -1.5149967090    7.5749835450    7.5749835450
   V   -3.0299934180    6.0599868360    9.0899802540
   V   -4.5449901270    4.5449901270   10.6049769630
   V   -6.0599868360    3.0299934180   12.1199736720
   V   -7.5749835450    1.5149967090   13.6349703810
   V   -3.0299934180    9.0899802540    9.0899802540
   V   -4.5449901270    7.5749835450   10.6049769630
   V   -6.0599868360    6.0599868360   12.1199736720
   V   -7.5749835450    4.5449901270   13.6349703810
   V   -9.0899802540    3.0299934180   15.1499670900
   V    4.5449901270    4.5449901270    4.5449901270
   V    3.0299934180    3.0299934180    6.0599868360
   V    1.5149967090    1.5149967090    7.5749835450
   V    0.0000000000    0.0000000000    9.0899802540
   V   -1.5149967090   -1.5149967090   10.6049769630
   V    3.0299934180    6.0599868360    6.0599868360
   V    1.5149967090    4.5449901270    7.5749835450
   V    0.0000000000    3.0299934180    9.0899802540
   V   -1.5149967090    1.5149967090   10.6049769630
   V   -3.0299934180    0.0000000000   12.1199736720
   V    1.5149967090    7.5749835450    7.5749835450
   V    0.0000000000    6.0599868360    9.0899802540
   V   -1.5149967090    4.5449901270   10.6049769630
   V   -3.0299934180    3.0299934180   12.1199736720
   V   -4.5449901270    1.5149967090   13.6349703810
   V    0.0000000000    9.0899802540    9.0899802540
   V   -1.5149967090    7.5749835450   10.6049769630
   V   -3.0299934180    6.0599868360   12.1199736720
   V   -4.5449901270    4.5449901270   13.6349703810
   V   -6.0599868360    3.0299934180   15.1499670900
   V   -1.5149967090   10.6049769630   10.6049769630
   V   -3.0299934180    9.0899802540   12.1199736720
   V   -4.5449901270    7.5749835450   13.6349703810
   V   -6.0599868360    6.0599868360   15.1499670900
   V   -7.5749835450    4.5449901270   16.6649637990
   V    6.0599868360    6.0599868360    6.0599868360
   V    4.5449901270    4.5449901270    7.5749835450
   V    3.0299934180    3.0299934180    9.0899802540
   V    1.5149967090    1.5149967090   10.6049769630
   V    0.0000000000    0.0000000000   12.1199736720
   V    4.5449901270    7.5749835450    7.5749835450
   V    3.0299934180    6.0599868360    9.0899802540
   V    1.5149967090    4.5449901270   10.6049769630
   V    0.0000000000    3.0299934180   12.1199736720
   V   -1.5149967090    1.5149967090   13.6349703810
   V    3.0299934180    9.0899802540    9.0899802540
   V    1.5149967090    7.5749835450   10.6049769630
   V    0.0000000000    6.0599868360   12.1199736720
   V   -1.5149967090    4.5449901270   13.6349703810
   V   -3.0299934180    3.0299934180   15.1499670900
   V    1.5149967090   10.6049769630   10.6049769630
   V    0.0000000000    9.0899802540   12.1199736720
   V   -1.5149967090    7.5749835450   13.6349703810
   V   -3.0299934180    6.0599868360   15.1499670900
   V   -4.5449901270    4.5449901270   16.6649637990
   V    0.0000000000   12.1199736720   12.1199736720
   V   -1.5149967090   10.6049769630   13.6349703810
   V   -3.0299934180    9.0899802540   15.1499670900
   V   -4.5449901270    7.5749835450   16.6649637990
   V   -6.0599868360    6.0599868360   18.1799605080
K_POINTS {automatic}
2 2 2  0 0 0


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