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cu_111_surface_and_k-points_sampling [2015/05/29 08:11]
cu_111_surface_and_k-points_sampling [2015/05/29 08:11]
krejcio
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 +Since we know, that the lattice parameter is 3.66 Angstrom, here is the structure for testing the sufficiency of the k-points sampling of the IBZ.
 +The geometry is in Cu_111.bas file:
 +     5
 +  29    0.00000 ​   1.49419 ​  ​10.00000
 +  29    0.00000 ​   0.00000 ​  ​12.11310
 +  29    1.29401 ​   0.74709 ​  ​14.22620
 +  29    0.00000 ​   1.49419 ​  ​16.33931
 +  29    0.00000 ​   0.00000 ​  ​18.45241
 +And the lattice vector for the Cu (111) surface is in Cu_111.lvs:
 +   ​2.58801 ​   0.00000 ​   0.00000
 +   ​1.29401 ​   2.24128 ​   0.00000
 +   ​0.00000 ​   0.00000 ​  ​99.99999
 +The last 2 layers will be fixed during optimization,​ therefore FRAGMENTS file contains:
 +  0
 +  1
 +  2
 +  4       1 1 1
 +  5       1 1 1
 +The amount of the k-points is not known, therefore one should check, whether the total energy and geometry changes with amount of the k-points. For this reason 3 files containing 8, 18 and 32 k-points:
 +Cu_111.8.kpts contains 4x4 k-points reduced to 8 k-points by inversion:
 +           8
 +   ​-0.91042715 ​  ​-0.52563387 ​   0.00000000 ​          ​0.12500000
 +   ​-0.91042715 ​   0.17521401 ​   0.00000000 ​          ​0.12500000
 +   ​-0.91042715 ​   0.87606192 ​   0.00000000 ​          ​0.12500000
 +   ​-0.91042715 ​  ​-1.22648176 ​   0.00000000 ​          ​0.12500000
 +   ​-0.30347571 ​  ​-0.87605917 ​   0.00000000 ​          ​0.12500000
 +   ​-0.30347571 ​  ​-0.17521130 ​   0.00000000 ​          ​0.12500000
 +   ​-0.30347571 ​   0.52563661 ​   0.00000000 ​          ​0.12500000
 +   ​-0.30347571 ​   1.22648454 ​   0.00000000 ​          ​0.12500000
 +Cu_111.18.kpts contains 6x6 k-points reduced to 18 k-points by inversion:
 +          18
 +   ​-1.01158571 ​  ​-0.58403766 ​   0.00000000 ​          ​0.05555556
 +   ​-1.01158571 ​  ​-0.11680572 ​   0.00000000 ​          ​0.05555556
 +   ​-1.01158571 ​   0.35042620 ​   0.00000000 ​          ​0.05555556
 +   ​-1.01158571 ​   0.81765813 ​   0.00000000 ​          ​0.05555556
 +    1.41621998 ​  ​-0.11681113 ​   0.00000000 ​          ​0.05555556
 +   ​-1.01158571 ​  ​-1.05126962 ​   0.00000000 ​          ​0.05555556
 +   ​-0.60695142 ​  ​-0.81765449 ​   0.00000000 ​          ​0.05555556
 +   ​-0.60695142 ​  ​-0.35042259 ​   0.00000000 ​          ​0.05555556
 +   ​-0.60695142 ​   0.11680934 ​   0.00000000 ​          ​0.05555556
 +   ​-0.60695142 ​   0.58404124 ​   0.00000000 ​          ​0.05555556
 +   ​-0.60695142 ​   1.05127323 ​   0.00000000 ​          ​0.05555556
 +   ​-0.60695142 ​  ​-1.28488645 ​   0.00000000 ​          ​0.05555556
 +   ​-0.20231713 ​  ​-1.05127132 ​   0.00000000 ​          ​0.05555556
 +   ​-0.20231713 ​  ​-0.58403945 ​   0.00000000 ​          ​0.05555556
 +   ​-0.20231713 ​  ​-0.11680753 ​   0.00000000 ​          ​0.05555556
 +   ​-0.20231713 ​   0.35042441 ​   0.00000000 ​          ​0.05555556
 +   ​-0.20231713 ​   0.81765634 ​   0.00000000 ​          ​0.05555556
 +   ​-0.20231713 ​   1.28488827 ​   0.00000000 ​          ​0.05555556
 +Cu_111.32.kpts contains 8x8 k-points reduced to 32 k-points by inversion:
 +          32
 +   ​-1.06216502 ​  ​-0.61323953 ​   0.00000000 ​          ​0.03125000
 +   ​-1.06216502 ​  ​-0.26281559 ​   0.00000000 ​          ​0.03125000
 +   ​-1.06216502 ​   0.08760835 ​   0.00000000 ​          ​0.03125000
 +   ​-1.06216502 ​   0.43803230 ​   0.00000000 ​          ​0.03125000
 +   ​-1.06216502 ​   0.78845626 ​   0.00000000 ​          ​0.03125000
 +    1.36564067 ​  ​-0.26282105 ​   0.00000000 ​          ​0.03125000
 +    1.36564067 ​   0.08760300 ​   0.00000000 ​          ​0.03125000
 +   ​-1.06216502 ​  ​-0.96366343 ​   0.00000000 ​          ​0.03125000
 +   ​-0.75868928 ​  ​-0.78845221 ​   0.00000000 ​          ​0.03125000
 +   ​-0.75868928 ​  ​-0.43802825 ​   0.00000000 ​          ​0.03125000
 +   ​-0.75868928 ​  ​-0.08760429 ​   0.00000000 ​          ​0.03125000
 +   ​-0.75868928 ​   0.26281965 ​   0.00000000 ​          ​0.03125000
 +   ​-0.75868928 ​   0.61324358 ​   0.00000000 ​          ​0.03125000
 +   ​-0.75868928 ​   0.96366751 ​   0.00000000 ​          ​0.03125000
 +   ​-0.75868928 ​   1.31409144 ​   0.00000000 ​          ​0.03125000
 +   ​-0.75868928 ​  ​-1.13887617 ​   0.00000000 ​          ​0.03125000
 +   ​-0.45521358 ​  ​-0.96366483 ​   0.00000000 ​          ​0.03125000
 +   ​-0.45521358 ​  ​-0.61324090 ​   0.00000000 ​          ​0.03125000
 +   ​-0.45521358 ​  ​-0.26281694 ​   0.00000000 ​          ​0.03125000
 +   ​-0.45521358 ​   0.08760700 ​   0.00000000 ​          ​0.03125000
 +   ​-0.45521358 ​   0.43803096 ​   0.00000000 ​          ​0.03125000
 +   ​-0.45521358 ​   0.78845489 ​   0.00000000 ​          ​0.03125000
 +   ​-0.45521358 ​   1.13887882 ​   0.00000000 ​          ​0.03125000
 +   ​-0.45521358 ​  ​-1.31408879 ​   0.00000000 ​          ​0.03125000
 +   ​-0.15173785 ​  ​-1.13887751 ​   0.00000000 ​          ​0.03125000
 +   ​-0.15173785 ​  ​-0.78845352 ​   0.00000000 ​          ​0.03125000
 +   ​-0.15173785 ​  ​-0.43802959 ​   0.00000000 ​          ​0.03125000
 +   ​-0.15173785 ​  ​-0.08760565 ​   0.00000000 ​          ​0.03125000
 +   ​-0.15173785 ​   0.26281831 ​   0.00000000 ​          ​0.03125000
 +   ​-0.15173785 ​   0.61324227 ​   0.00000000 ​          ​0.03125000
 +   ​-0.15173785 ​   0.96366620 ​   0.00000000 ​          ​0.03125000
 +   ​-0.15173785 ​   1.31409013 ​   0.00000000 ​          ​0.03125000
  
 +
 +The fireball.in should look like this:
 +  &OPTION
 +  basisfile = Cu_111.bas
 +  lvsfile = Cu_111.lvs
 +  kptpreference = Cu_111.XXX.kpts
 +  nstepf = 5000
 +  iquench = -6     ! -1 = MDmin, -6 = FIRE optimization
 +  icluster = 0
 +  iqout = 1
 +  dt = 0.5
 +  &END
 +  &OUTPUT
 +  iwrtxyz = 1
 +  &END
 +
 +Now the optimization should be performed with different k-point sampling. The total energy could be simply checked from the output file:
 +  grep "​ETOT"​ name_of_the_output_file | tail -1
 +
 +If the total energy and the geometry doesn'​t differ too much (comparing two different k-point sampling) then the lower amount of the k-points is considered as the sufficient one.
cu_111_surface_and_k-points_sampling.txt ยท Last modified: 2015/05/29 08:11 (external edit)