[Wien] Ce does not converge

[Peter Blaha]

A "lanthanide" is NEVER simple.

The 4f states in GGA are all at EF and form a very narrow band. Thus 
tiny changes in the potential move the 4f states relative to the broad 
s,d states and huge internal charge transfer can occur.

RKmax=7 for a 4f element is MUCH too small. Use at least  8, better 9-10

Use TEMP(S) with 6 mRy (at the beginning). It damps oszillations.

Use a good k-mesh. 1000 k-points are by a factor of 10 too small.

I'm not sure if GGA+U is very good for Ce metal, at least not for the 
low-volume fcc phase.

Am 29.01.2020 um 17:26 schrieb delamora:
> Dear WIEN2k community;
> I tried to make a spin polarized calculation the Ce metal;
> FCC a=b=c=5.16A with a U=5eV
> and also an antiferromagnetic calculation
> a=b=c/sqrt(2), c=5.16A
> Ce up; 0,0,0
> Ce dn; 1/2, 1/2, 1/2
> and they did not converge with cc=0.001
> 
> for the ferromagnetic calculation I did 140 iterations with RxK=7 and 
> #K=10,000
> :ENERGY convergence:  0 0 .0000693950000000
> :ENERGY convergence:  0 0 .0001091800000000
> :ENERGY convergence:  0 0 .0002001000000000
> :DIS  :  CHARGE DISTANCE       ( 0.0377909 for atom    1 spin 1)     
>   0.0820411
> :DIS  :  CHARGE DISTANCE       ( 0.0301614 for atom    1 spin 1)     
>   0.0685493
> :DIS  :  CHARGE DISTANCE       ( 0.0278653 for atom    1 spin 1)     
>   0.0641289
> 
> for the antiferromagnetic calculation I had RxK=7 and #K=1,000 and I did 
> 63 iterations
> 
> I find confusing that a simple calculation for a lanthanide element does 
> not converge.
> 
> Pablo
> 
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-- 
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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