I have some problems with the convergence of a GaAs supercell.
The Input file is:
Code: Select all
########################## Definition of cell #################################
acell 2.13678892749911E+01 2.13678892749911E+01 2.13678892749911E+01 bohr
rprim 1.0000000000E+00 0.0000000000E+00 0.0000000000E+00
0.0000000000E+00 1.0000000000E+00 0.0000000000E+00
0.0000000000E+00 0.0000000000E+00 1.0000000000E+00
########################### Definition of atoms ################################
natom 64
xangst
0.00000 0.00000 0.00000
1.41342 1.41342 1.41342
-0.00000 2.82685 2.82685
2.82685 -0.00000 2.82685
2.82685 2.82685 0.00000
4.24027 4.24027 1.41342
4.24027 1.41342 4.24027
1.41342 4.24027 4.24027
-0.00000 -0.00000 5.65370
1.41342 1.41342 7.06712
-0.00000 2.82685 8.48055
2.82685 -0.00000 8.48055
2.82685 2.82685 5.65370
4.24027 4.24027 7.06712
4.24027 1.41342 9.89397
1.41342 4.24027 9.89397
-0.00000 5.65370 0.00000
1.41342 7.06712 1.41342
-0.00000 8.48055 2.82685
2.82685 5.65370 2.82685
2.82685 8.48055 0.00000
4.24027 9.89397 1.41342
4.24027 7.06712 4.24027
1.41342 9.89397 4.24027
-0.00000 5.65370 5.65370
1.41342 7.06712 7.06712
-0.00000 8.48055 8.48055
2.82685 5.65370 8.48055
2.82685 8.48055 5.65370
4.24027 9.89397 7.06712
4.24027 7.06712 9.89397
1.41342 9.89397 9.89397
5.65370 0.00000 0.00000
7.06712 1.41342 1.41342
5.65370 2.82685 2.82685
8.48055 -0.00000 2.82685
8.48055 2.82685 0.00000
9.89397 4.24027 1.41342
9.89397 1.41342 4.24027
7.06712 4.24027 4.24027
5.65370 -0.00000 5.65370
7.06712 1.41342 7.06712
5.65370 2.82685 8.48055
8.48055 -0.00000 8.48055
8.48055 2.82685 5.65370
9.89397 4.24027 7.06712
9.89397 1.41342 9.89397
7.06712 4.24027 9.89397
5.65370 5.65370 0.00000
7.06712 7.06712 1.41342
5.65370 8.48055 2.82685
8.48055 5.65370 2.82685
8.48055 8.48055 0.00000
9.89397 9.89397 1.41342
9.89397 7.06712 4.24027
7.06712 9.89397 4.24027
5.65370 5.65370 5.65370
7.06712 7.06712 7.06712
5.65370 8.48055 8.48055
8.48055 5.65370 8.48055
8.48055 8.48055 5.65370
9.89397 9.89397 7.06712
9.89397 7.06712 9.89397
7.06712 9.89397 9.89397
ntypat 2
znucl 31 33
typat 1 2 1 1 1 2 2 2 1 2 1 1 1 2 2 2 1 2 1 1 1 2 2 2 1 2 1 1 1 2 2 2 1 2 1 1 1 2 2 2 1 2 1 1 1 2 2 2 1 2 1 1 1 2 2 2 1 2 1 1 1 2 2 2
chkprim 0 # dos not check for primitive unit-cells
########################## Definition of k-Points ##########################
kptopt 0 # 0 read nkpt, 2 for rf calculations
nkpt 1 # number of k-Points
##################### Definition of the planewave basis set #####################
ecut 30.0 # Maximal kinetic energy cut-off. in Hartree
######################## Exchange-correlation functional ########################
ixc 7 # LDA Perdew-Wang 92 functional
########################## Optimization of latice ##########################
ionmov 2 # optimization of atom positions with the Broyden-Fletcher-Goldfarb-Shanno Minimization-Method
optcell 2 # optimize cell
tolmxf 1e-7 # max gradient on ion or stress in cell optimization, RF 10-7, sonst 10-5
strfact 20 # stopping criterion for cell optimization
iscf 7 # Self-consistent calculation, using algorithm 7
ntime 500 # Max. number of ion/cell optimization steps
ecutsm 0.5 # needed for variable cell
dilatmx 1.2 # needed for variable cell
######################## definition of the SCF procedure ########################
toldff 1.0d-8 # SCF stopping criterion
nstep 3000 # Maximal number of SCF cycles
# iprcel 0 # Defines the SCF preconditioning scheme
diemac 13.0 # Sets value of the dielectric constant for preconditioning
# diecut 2.2 # Kinetic energy cutoff, controls the number of planewaves used to represent the dielectric matrix
# dielng 1.0775 # screening length (in Bohr) to model dielectric function
diemix 0.9 # Gives overall factor (0.0 - 1.0) of the preconditioned residual density/potential to be
# transferred in the SCF cycle
# dielam 0.5 # Gives the amount of occupied states with mean energy given by the highest level computed
# in the run, used for the extrapolation of the dielectric matrix. Used when iprcel >= 21
diegap 1.42 eV # Gives a rough estimation of the dielectric gap between the
# highest energy level computed in the run, and the set of
# bands not represented. Used to extrapolate dielectric matrix
# when iprcel >= 21
I need the big supercell for further calculations.
Does someone know which paramters can help me to converge the calulcation?
For this Input file only the first iteration converge. All further iterations do not converge with limit SCF Cyles.
Chris