Alpha-SiO2

Exercise : Determine the ¹⁷O C_q value and the Si and O schieldings.

• INCAR

  SYSTEM      = Si O2

  GGA          = PE
  ISTART       = 1
  ICHARG       = 0
  INIWAV       = 1
  LREAL        =  AUTO
  ISYM         = 2
  ISPIN        = 1

Ionic minimisation
  NSW          = 0
  ISIF         = 2
  IBRION       = 2
#  EDIFFG        = -2E-2
  POTIM        = 0.1

Electronic minimisation
  IALGO        = 38

  LWAVE        = .TRUE.

  EMIN         =   -20.0
  EMAX         =   10.0
  NEDOS        = 1601

EFG Calculation
  LEFG         = .TRUE.
  QUAD_EFG     = 0.0 25.5

Chemical Shift
  PREC         = Normal    # nice
  ENCUT        = 400.0      # typically higher cutoffs than usual are needed
  ISMEAR = 0; SIGMA= 0.1 # no fancy smearings, SIGMA sufficiently small
  EDIFF        = 1E-9      # you'd need much smaller EDIFFs.

  LCHIMAG      = .TRUE.   # to switch on linear response for chemical shifts
  DQ           = 0.001         # often the default is sufficient
  ICHIBARE     = 1       # often the default is sufficient
  LNMR_SYM_RED = .TRUE. # be on the safe side
  NSLPLINE     = .TRUE.  # only needed if LREAL is NOT set.
  LREAL        = A          # helps for speed for large systems, not needed
  NBANDS       = 30       # to safe memory, ??? = NELECT/2 

• KPOINTS

automatic mesh
0
Auto
20

• POSCAR

O2 Si1
   1.00000000000000
     4.6040000915999997    0.0000000000000000    0.0000000000000000
    -2.3020000457999998    3.9871810383000001    0.0000000000000000
     0.0000000000000000    0.0000000000000000    5.2069997787000002
   Si   O
     3     6
Direct
  0.4436617824484789 -0.0000000000000000  0.3333333429999996
 -0.0000000000000000  0.4436617824484789  0.6666666870000029
  0.5563382175515210  0.5563382175515210 -0.0000000000000000
  0.3926661416221499  0.3062177364999842  0.2428214976299141
  0.6937822635000156  0.0864484051221655  0.5761548406299137
  0.9135515948778347  0.6073338583778505  0.9094881546299145
  0.3062177364999842  0.3926661416221499  0.7571785323700884
  0.0864484051221655  0.6937822635000156  0.4238451593700863
  0.6073338583778505  0.9135515948778347  0.0905118383700884

Download

Ni111clean_400eV.tgz

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