[Wien] cnorm for Laplacian calculation

[Dr. Georg Eickerling]

Dear Prof. Blaha,

thank you for the reply.

> I don't know how exactly you got the laplacian, but my first guess
> concerning the factor 2 would be that you did not consider the spin.

I followed the "guide" you gave me a while back here on the mailing list:

 >You can use lapw0. In case.in0 specify as option   36   (instead if 13)
 >and put R2V instead of NR2V.
 >
 >(See vxclm2.f in SRC_lapw0)



I did my (non-spinpolarized) SCF run as usual and then modified in0
to use option 36 and r2v instead of the defaults.

> 
> In lapw0 everything is done spin-polarized, even in a non-spinpolarized
> calculation and one has to add spin-up and dn laplacians to get the
> total.

I obtain one r2v file and in my working dir I do not see any
files indicating an "up/down" output. So I followed your "old" advice


 >The file case.r2v contains the laplacian in the same functional form as
 >the density or the potential is usually stored. Thus you can use this file
 >instead of case.clmval  and plot the Laplacian with   x lapw5
 >(you need to   cp case.r2v case.clmval    before running lapw5).

and used the r2v file "as it is" to plot nabla**2.

> I guess the rest is ok. The normalization of clmsum and clmval files are
> different (only inside the spheres!), this explains the factor sqrt(4pi),
> but the r2v file has the "clmval" normalization.

Thank you for clarifying this. I will do some further tests and try to 
find out
what is causing the deviations I observe - I do not see a mistake in
my "procedure", yet.


regards

Georg Eickerling


> 
> 
> Dr. Georg Eickerling schrieb:
>> Dear WIEN users,
>>
>> I have a question concerning the use of LAPW5 to calculate the Laplacian 
>> of the Density on a grid.
>>
>> Using lapw0  [WIEN2k_08.1 (Release 14/12/2007)] I can obtain an r2v file 
>> containing the information
>> about the Laplacian and copying the r2v to clmval I can use lapw5 to 
>> obtain grid files.
>>
>> I specify atomic units in the lapw5 input to keep WIEN from applying 
>> some conversion factors from
>> e bohr-3 to e A-3 which would be useless in  this case and in addition I 
>> specify the keyword VAL.
>>
>> This works all well and the plots in XCrysden look resonable but 
>> comparing the absolute values from WIEN
>> to those obtained by experiment WIEN gives results which are too small 
>> by something close to a factor of 2
>>   (which seems not to be "real" as the topological parameters obtained 
>> by WIEN's aim at the bond critical
>> points are VERY close to the experimental values).
>>
>> In lapw5 I can specify "TOT" of "VAL" for the "normalization" which 
>> results in a division by a factor Sqrt(4Pi) in the
>> case of using "TOT". My first (general) question is: What is the reason 
>> for this additional factor for the total density?
>>
>> Any then the second question: What would be the "proper" way to obtain 
>> the Laplacian in atomic units with LAPW5,
>> should I use VAL or TOT or is there some other normalization/unit 
>> conversion I would have to do?
>>
>> Thanks in advance for any help!
>>
>> Georg Eickerling
>>
>>
>>
>>
> 


-- 
============================
Dr. Georg Eickerling
Universitaet Augsburg
Institut fuer Physik
Lehrstuhl fuer Chemische Physik und Materialwissenschaften
Universitaetsstr. 1
86159 Augsburg

E-Mail:	georg.eickerling at physik.uni-augsburg.de
Phone:	+49-821-598-3354
FAX:	+49-821-598-3227
WWW:	http://www.physik.uni-augsburg.de/cpm/
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