[Wien] Fe slab
Lukasz Plucinski
pluto at physics.ucdavis.edu
Sat Jul 5 11:17:20 CEST 2008
Hello Prof. Blaha,
Thank you for the detailed answer. Tonight calculation has converged
after 52 iterations !!
I think in larger slab its easier to separate surface states. I thought
there is enough vacuum in my struct file, I will test this by comparing
results with different vacuum size.
Lukasz
Peter Blaha wrote:
> Why would you use such a struct file ?
>
> a) With limited experience, start with small models, 5 or 7 layers only.
> b) I don't know how this struct file was created, but for sure a 15
> layer Fe(001) slab can have inversion symmetry and I'm pretty sure that
> WIEN should be able to find the proper symmetry (sgroup) when you allow
> for it. Remove ALL numbering for atomes (Fe1,2,3,...) and run the
> initialization. sgroup (or nn in most cases) should always group 2 atoms
> together (make them equivalent, except the center). sgroup should also
> shift the atoms along z.
> Your calculations will be 4 times faster when you have inversion symmetry!
> c) When going for thicker slabs, you should also improve your vacuum. It
> does not make sense to go to a thick slab, but have surface-surface
> interactions through the vacuum.
> d) k-mesh: why would one use a "2" fold k-mesh in z-direction. With
> recent WIEN2k versions you can also specify a 21x21x1 mesh for kgen.
> e) Some cases may need more than 40 iterations. As long as it does not
> diverge, just continue.
> f) Eventually TEMP with some broadening (0.005) may help convergence.
> However, in particular with magnetic systems, make sure that the
> broadening does not influence your magnetism and recheck with smaller
> broadening.
>
> Lukasz Plucinski schrieb:
>
>> I am trying to do spin-polarized slab calculation on Fe(001). It runs
>> ok, but does not converge (fluctuates) after 40 iterations. I tried with
>> up 1000 k-points (21x21x2 - I guess its already too much), 0.05 mixing
>> factor, and both PBE(96) and W-C(06) GGAs. Other settings default,
>> spin-polarized calculation right away.
>>
>> Which parameters should I try to change next ?
>>
>> Struct file below.
>>
>> Lukasz
>>
>>
>>
>> Fe-slab-001
>>
>> P LATTICE,NONEQUIV.ATOMS:
>> 15
>> MODE OF CALC=RELA
>> unit=ang
>> 5.416902 5.416902 54.169021 90.000000 90.000000
>> 90.000000
>> ATOM -1: X=0.00000000 Y=0.00000000 Z=0.10000000
>> MULT= 1 ISPLIT=-2
>> Fe1 NPT= 781 R0=0.00010000 RMT= 2.3450 Z:
>> 26.0
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -2: X=0.50000000 Y=0.50000000 Z=0.15000000
>> MULT= 1 ISPLIT=-2
>> Fe2 NPT= 781 R0=0.00010000 RMT= 2.3450 Z:
>> 26.0
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -3: X=0.00000000 Y=0.00000000 Z=0.20000000
>> MULT= 1 ISPLIT=-2
>> Fe3 NPT= 781 R0=0.00010000 RMT= 2.3450 Z:
>> 26.0
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -4: X=0.50000000 Y=0.50000000 Z=0.25000000
>> MULT= 1 ISPLIT=-2
>> Fe4 NPT= 781 R0=0.00010000 RMT= 2.3450 Z:
>> 26.0
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -5: X=0.00000000 Y=0.00000000 Z=0.30000000
>> MULT= 1 ISPLIT=-2
>> Fe5 NPT= 781 R0=0.00010000 RMT= 2.3450 Z:
>> 26.0
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -6: X=0.50000000 Y=0.50000000 Z=0.35000000
>> MULT= 1 ISPLIT=-2
>> Fe6 NPT= 781 R0=0.00010000 RMT= 2.3450 Z:
>> 26.0
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -7: X=0.00000000 Y=0.00000000 Z=0.40000000
>> MULT= 1 ISPLIT=-2
>> Fe7 NPT= 781 R0=0.00010000 RMT= 2.3450 Z:
>> 26.0
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -8: X=0.50000000 Y=0.50000000 Z=0.45000000
>> MULT= 1 ISPLIT=-2
>> Fe8 NPT= 781 R0=0.00010000 RMT= 2.3450 Z:
>> 26.0
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -9: X=0.00000000 Y=0.00000000 Z=0.50000000
>> MULT= 1 ISPLIT=-2
>> Fe9 NPT= 781 R0=0.00010000 RMT= 2.3450 Z:
>> 26.0
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -10: X=0.50000000 Y=0.50000000 Z=0.55000000
>> MULT= 1 ISPLIT=-2
>> Fe10 NPT= 781 R0=0.00010000 RMT= 2.3450 Z:
>> 26.0
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -11: X=0.00000000 Y=0.00000000 Z=0.60000000
>> MULT= 1 ISPLIT=-2
>> Fe11 NPT= 781 R0=0.00010000 RMT= 2.3450 Z:
>> 26.0
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -12: X=0.50000000 Y=0.50000000 Z=0.65000000
>> MULT= 1 ISPLIT=-2
>> Fe12 NPT= 781 R0=0.00010000 RMT= 2.3450 Z:
>> 26.0
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -13: X=0.00000000 Y=0.00000000 Z=0.70000000
>> MULT= 1 ISPLIT=-2
>> Fe13 NPT= 781 R0=0.00010000 RMT= 2.3450 Z:
>> 26.0
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -14: X=0.50000000 Y=0.50000000 Z=0.75000000
>> MULT= 1 ISPLIT=-2
>> Fe14 NPT= 781 R0=0.00010000 RMT= 2.3450 Z:
>> 26.0
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -15: X=0.00000000 Y=0.00000000 Z=0.80000000
>> MULT= 1 ISPLIT=-2
>> Fe15 NPT= 781 R0=0.00010000 RMT= 2.3450 Z:
>> 26.0
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> 8 NUMBER OF SYMMETRY OPERATIONS
>> -1 0 0 0.0000000
>> 0-1 0 0.0000000
>> 0 0 1 0.0000000
>> 1
>> -1 0 0 0.0000000
>> 0 1 0 0.0000000
>> 0 0 1 0.0000000
>> 2
>> 0-1 0 0.0000000
>> -1 0 0 0.0000000
>> 0 0 1 0.0000000
>> 3
>> 0 1 0 0.0000000
>> -1 0 0 0.0000000
>> 0 0 1 0.0000000
>> 4
>> 0-1 0 0.0000000
>> 1 0 0 0.0000000
>> 0 0 1 0.0000000
>> 5
>> 0 1 0 0.0000000
>> 1 0 0 0.0000000
>> 0 0 1 0.0000000
>> 6
>> 1 0 0 0.0000000
>> 0-1 0 0.0000000
>> 0 0 1 0.0000000
>> 7
>> 1 0 0 0.0000000
>> 0 1 0 0.0000000
>> 0 0 1 0.0000000
>> 8
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