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虫号: 1988538
注册: 2012-09-10
专业: 理论和计算化学

[求助] 如何计算clamped-ion 和free_stress 状态下的介电常数

这是本人的.in文件，请问告诉要如何修改才能计算上面所说的介电常数
ndtset 3
#set 1 : Initial self-consistent run
iscf1 5
  kptopt1 1
  tolvrs1 1.0d-18  #need excellent convergence of GS quantities for RF runs
# Set 2 : Calculate the ddk wf's - needed for piezoelectric tensor and
#       Born effective charges in dataset 3
  getwfk2  -1
iscf2  -3       #this option is needed for ddk
  kptopt2 2       #use time-reversal symmetry only for k points
nqpt2 1       #one wave vector will be specified
   qpt2 0 0 0 #need to specify gamma point
  rfelfd2 2       #set for ddk wf's
rfdir2 1 1 1 #full set of directions needed
  tolwfr2 1.0d-20  #only wf convergence can be monitored here
# Set 3 : response-function calculations for all needed perturbations
  getddk3  -1
  getwfk3  -2
iscf3 5
  kptopt3 2       #use time-reversal symmetry only for k points
nqpt3 1
   qpt3 0 0 0
  rfphon3 1       #do atomic displacement perturbation
rfatpol3 1 4    #do for all atoms
  rfstrs3 3       #do strain perturbation
  rfelfd3 3
  efield3 0.0001 0.0001 0.0001
rfdir3 1 1 1 #the full set of directions is needed
  tolvrs3 1.0d-10  #need reasonable convergence of 1st-order quantities
#Common input data
# acell  COPY RELAXED RESULT FROM PREVIOUS CALCULATION
# Here is a default value, for automatic testing : suppress it and fill the previous line
acell  6.0591285222E+00  6.0591285222E+00  9.7876758521E+00
rprim sqrt(0.75)  0.5  0.0 #hexagonal primitive vectors must be
      -sqrt(0.75)  0.5  0.0 #specified with high accuracy to be
      0.0       0.0  1.0 #sure that the symmetry is recognized
                              #and preserved in the optimization
                              #process
#Definition of the atom types and atoms
ntypat 2
  znucl 8  30
  natom 4
  typat 1 1 2 2
#Starting approximation for atomic positions in REDUCED coordinates
xred    3.3333333333E-01  6.6666666667E-01  3.8063479051E-01
      -3.3333333333E-01 -6.6666666667E-01  8.8063479051E-01
      3.3333333333E-01  6.6666666667E-01  1.9652094936E-03
      -3.3333333333E-01 -6.6666666667E-01  5.0196520949E-01
#Gives the number of bands, explicitely (do not take the default)
  nband 20             # For an insulator (if described correctly as an
                     # insulator by DFT), conduction bands should not
                     # be included in response-function calculations
#Definition of the plane wave basis set
ecut 50          # Maximum kinetic energy cutoff (Hartree)
ecutsm 0.5          # Smoothing energy needed for lattice paramete
                     # optimization.  This will be retained for
                     # consistency throughout.
#Definition of the k-point grid
kptopt 1             # Use symmetry and treat only inequivalent points
  ngkpt 8 8 8       # 4x4x4 Monkhorst-Pack grid
nshiftk 1             # Use one copy of grid only (default)
shiftk 0.0 0.0 0.5 # This choice of origin for the k point grid
                     # preserves the hexagonal symmetry of the grid,
                     # which would be broken by the default choice.
#Definition of the self-consistency procedure
diemac 3.0          # Model dielectric preconditioner
iscf 5             # Use conjugate-gradient SCF cycle
  nstep 100          # Maxiumum number of SCF iterations
# enforce calculation of forces at each SCF step
optforces 1

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