[Wien] Poisson and clmsum

[Georg Eickerling]

Dear Wien users,

now I have to join this thread, because this last piece of information sounds 
interesting also to me.

I am doing topological analyses of electron densities/Laplacians via WIEN2k and the
discontinuities at the MT radii spoil basically any nabla² rho(r) map
one tries to make with WIEN2k. I have tried many things (large RKMAX, lmax, APW vs. LAPW)
but tiny steps at the MT boundary remain in rho(r) and therefore in all its derivatives. 
The information about generating a ".lcore" file is new to me - what does this file actually do
if it exists and when should it be generated, already for the init or the scf step?

best regards

Georg Eickerling


On 11/22/2016 07:51 PM, Laurence Marks wrote:
> N.B., there can also be a discontinuity in the charge (small) due to the
> tails of the core states which can be eliminated by doing "touch .lcore".
> 
> On Mon, Nov 21, 2016 at 8:36 AM, Laurence Marks <L-marks at northwestern.edu>
> wrote:
> 
>> APW+lo methods have a step in the gradient of the density at the RMT. To
>> avoid this use a lapw basis set: to reduce it increase RKMAX.
>>
>> ---
>> Professor Laurence Marks
>> "Research is to see what everybody else has seen, and to think what nobody
>> else has thought", Albert Szent-Gyorgi
>> http://www.numis.northwestern.edu
>> Corrosion in 4D http://MURI4D.numis.northwestern.edu
>> Partner of the CFW 100% gender equity project, www.cfw.org/100-percent
>> Co-Editor, Acta Cryst A
>>
>>
>> On Nov 21, 2016 07:39, "John Rundgren" <jru at kth.se> wrote:
>>
>>> Dear Peter Blaha and Gavin Abo,
>>>
>>> Non-overlapping muffin-tin spheres are used by WIEN2k and my LEED program
>>> eeasisss (Elastic Electron-Atom Scattering in Solids and Surface Slabs).
>>> But RMT(setrmt_lapw) is not automatically the best choice for
>>> RMT(eeasisss). LEED touching radii of atoms depend on exchange-correlation
>>> interaction between crystal electron gas (the WIEN2k electrons) and an
>>> incident LEED electron (energy 20-500 eV).
>>>
>>> This is a N+1 electron scattering situation, where "N" signifies the
>>> WIEN2k electrons and "1" an alien LEED electron.
>>>
>>> W2k can be reconciled with LEED using an atomic sphere approximation
>>> (ASA) extending into the Fourier expansion realm of W2k. A while ago you
>>> (P.B. and G.A.) suggested an ASA routine, in which I now use Poisson
>>> differentiation of vcoul_ASA in order to obtain clmsum_ASA. I consider the
>>> case LM=(0,0), sufficient for current LEED.
>>>
>>> The considered structure is a supercell = a surface slab 15 layers thick,
>>> where layers 1-2 and 14-15 are C-O and O-C, respectively. Mirror symmetry
>>> about layer 8. At the C-O layers vcoul_ASA(0,0) is continuous across the
>>> RMT radius, but clmsum_ASA(0,0) versus radius shows a step of the order of
>>> 10%.
>>>
>>> Is the step k-point dependent? It does not seem so. With 16 and 48
>>> k-points the clmsum_ASA(0,0) steps are preserved within 6 digits.
>>>
>>> I shall be glad to supply the code. When the described numerical error is
>>> fixed, WIEN2k and eeasisss can be re-run self-consistently within the model
>>> of non-overlapping muffin-tin atoms.
>>>
>>> Regards,
>>> John Rundgren
>>>
>>> KTH
>>>
>>>
>>>
>>>
> 
> 
> 
> 
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-- 
============================
PD Dr. Georg Eickerling
Universität Augsburg
Institut für Physik
Lehrstuhl für Chemische Physik und Materialwissenschaften
Universitätsstr. 1
86159 Augsburg

E-Mail:	georg.eickerling at physik.uni-augsburg.de
Phone:	+49-821-598-3362
FAX:	+49-821-598-3227
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