[Wien] Running LDA+U from w2web

[Yurko Natanzon]

Dear wien2k users,
I'm a novice in this program and began learning wien2k from using
w2web as described in Quick Start section of the manual. I want to
repeat the standard TiC calculation with LDA+U(SIC) and compare the
results with standard GGA.

What I don't know is how to run LDA+U from w2web. There are only three
options in lstart: GGA-PBE, GGA-WC and LSDA. Which one to choose in
this case?

Further, in SCF section there is a tick "orbital pot (LDA+U)".
however, if I choose it, I get an error "Can't read file
//home/natanzon/wien2k/jobs/TiC/TiC.indmc."

I would be glad if you tell me which modifications should be provided
in TiC example from the manual, if I want to do LDA+U(SIC)
calculation.

I've carefully read the 7.2 section of the manual and got aquainted
with the input file format for ORB program, but I don't know how to
specify it using w2web and run SCF calculation. I'm running Wien2k_08
in serial mode on Intel Core 2 Duo Linux desktop.

thanks in advance,
Yuriy Natanzon

2008/5/16 Peter Blaha <pblaha at theochem.tuwien.ac.at>:
> For "non-cubic" symmetry ("negative" atomic numbering in case.struct) we
> use the tesserial harmonics as you have given below in your first
> definition (without the sqrt 4pi /2l+1 factor.
>
> For "cubic harmonics", there is in principle only ONE independent C4
> coefficient, which is multiplied with a complicated linear combination
> of Y40, Y44 and Y4-4.
> You can find the definition eg. in lapw0 (or lapw5) in some subroutines
> (common /norm_cub/)
> The individual potential components c40 and c44 may not obay these
> rules, since the xcpot part is splitted "arbitrarely".
>
>
> Maurits W. Haverkort schrieb:
>> Dear all
>>
>> I've been looking into the effects of non-spherical potentials in DFT
>> and run into the problem that I do not understand the normalization used
>> for the lattice harmonics in Wien2k. In order to see if I understand
>> correctly what Wien2k does I calculated two times Bcc Fe. Once with the
>> C4 axes in the x, y, and z direction and once I rotated the input file
>> and placed the C3 axes in the z direction (In order to do so I created a
>> super cell and lowered the appearing symmetry)
>>
>> In a cubic symmetry I would expect that if the C4 axes is // x,y, and z,
>> the potential looks like V(r) (Y_{4,-4} +Y_{4,4}+\sqrt(14/5) Y_{4,0})
>> In a cubic symmetry with the C3 axes // z and a C2 axes // y and the C4
>> axes in the (-1,\sqrt{3},\sqrt{2}) direction I would expect the
>> potential to be V(r) (Y_{4,-3} - Y_{4,3} - \sqrt{7/10} Y_{4,0}).
>>
>> The functions Y_{l,m} are the normalized spherical harmonics as defined
>> on http://mathworld.wolfram.com/SphericalHarmonic.html or
>> http://en.wikipedia.org/wiki/Spherical_harmonic
>>
>> In the file case.vtotal I find:
>> For the struct file with the C4 axes in the z direction I find a ratio
>> of \sqrt{14/5} (for large or small r) between the two components of the
>> potential.
>> For the struct file with the C3 axes in the z direction I find a ratio
>> of 6/10 between the two components of the potential.
>>
>> My question is how are the lattice harmonics as used in Wien2k defined
>> with respect to the normalized spherical harmonics.
>>
>> What I found out so far:
>>
>> The spherical harmonics used are (as in the subroutine ylm.f) defined to
>> be normalized i.e. <Ylm | Ylm>=1 and with the (additional) CS phase (-1)^m.
>>
>> (Upto the factor of (-1)^m this is the same as on
>> http://mathworld.wolfram.com/SphericalHarmonic.html or
>> http://en.wikipedia.org/wiki/Spherical_harmonic)
>>
>> One can define normalized tesseral harmonics, which are real functions as:
>>
>> Z_{m}^{(l)}=N(m) (Y_{l,-Abs(m)} + s(m) Y_{l,Abs(m)})
>> with N(m)=1,\sqrt(1/2) i ^(1-Sign(m))/2
>> and s(m)=0,(-1)^m Sign(m)
>> for m=0 , m<>0 respectively.
>>
>> (These are the standard real functions one likes to work with)
>>
>> For potential expansions one not always likes to work with normalized
>> functions and renormalized spherical harmonics (or tesseral harmonics)
>> can be defined with an additional pre-factor:
>> C_(l,m) = \sqrt((4 \pi)/(2l+1)) Y_(l,m)
>>
>> Thanks in advance!
>> Maurits
>>
>> (Calculations done with Wien2k V8.1 linux MKL 9.1 ifort)
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-- 
Yurko (aka Yuriy, Iurii, Jurij etc) Natanzon
PhD Student
Henryk Niewodniczan`ski Institute of Nuclear Physics
Polish Academy of Sciences
ul. Radzikowskiego 152,
31-342 Krako`w, Poland
Email: Yurii.Natanzon at ifj.edu.pl, yurko.natanzon at gmail.com