[Wien] (no subject)

[Laurence Marks]

While there is some rationale to changing the angles to 90, this is in
general not appropriate.

Rather than doing this I suggest working through the examples in the Wien2k
documentation. There are also examples in the Lecture notes on the web
page. This will teach you a lot.

On Thu, Apr 23, 2015 at 10:02 AM, delamora <delamora at unam.mx> wrote:

> The simplest perivskite is
> a=b=c
> alpha=beta=gamma=90
> A: 1/2,1/2,1/2
> B: 0,0,0
> O: 1/2,0,0
>     0,1/2,0
>     0,0,1/2
> space group 221
> so, if you have alpha=89.999 you can adjust to 90.
> Now, if you have alpha=89.9 you can adjust to 90 for learning purposes,
> the calculation will be quite fast, but the final calculation you should
> use 89.9 and the pbnm group that has lower symmetry
>     Pablo
>
> ________________________________________
> De: wien-bounces at zeus.theochem.tuwien.ac.at <
> wien-bounces at zeus.theochem.tuwien.ac.at> en nombre de Víctor Luaña Cabal <
> victor at fluor.quimica.uniovi.es>
> Enviado: jueves, 23 de abril de 2015 07:54 a. m.
> Para: A Mailing list for WIEN2k users
> Cc: Victor Luaña
> Asunto: Re: [Wien] (no subject)
>
> On Thu, Apr 23, 2015 at 05:56:00PM +0530, Shakeel Khandy wrote:
> > I m a beginner and i want to study a compound of ABO3 type pervoskite
> with
> > space group *pbnm*.I have got confused with the atomic positions of
> > *pbnm *spacegroup.
> > Although the experimental atomic positions are in my hand,but the problem
> > lies in the negative atomic positions given by experimental data. Is
> there
> > any other method to have the required atomic positions.
>
> Shakeel,
>
> 1) The crystallographic description of coordinates assumes periodicity.
>    So x=-0.12 is identical to 1+x=1-0.12. Any crystallographer is trained
>    to do the operation quickly and the easy way is thinking
>
>     1 = 0.999999999(10)
>           --------- as mant 9's as it is needed
>
> 2) ¿Don't have a professor to traing you? ¿Don't have books on
>    crystallography available?
>
> 3) Assuming the answers are NO in both cases let me recommend
>    you some materials appropriate to the level of your question
>
> a) My own slides on the subject
>
>    <http://azufre.quimica.uniovi.es/DetEst/>
>
>    Sorry by the spanish. Use google translate as you need.
>
> b) An excellent and recent manual by italian crystallographers:
>
>    C. Giacovazzo, Ed. Fundamentals of crystallography, IUCr & Oxford Univ
> Press
>    IUCR: 0198555784, 1992
>
>    There is a new edition, but I don't have it al hand.
>
> 4) This type of question should be solved by your prof./teacher
>
> Good luck,
>           Dr. Víctor Luaña
> --
>      .  .    DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
>     / `' \   "I think the problem, to be quite honest with you,
>    /(o)(o)\  is that you have never actually known what the question is."
>   /`. \/ .'\
>  /   '`'`   \ "Lo mediocre es peor que lo bueno, pero también es peor
>  |  \'`'`/  | que lo malo, porque la mediocridad no es un grado, es una
>  |  |'`'`|  | actitud"
>   \/`'`'`'\/          -- Jorge Wasenberg, 2015
> ===(((==)))==================================+=========================
> ! Dr.Víctor Luaña, in silico chemist & prof. ! Mediocre is worse than
> ! Departamento de Química Física y Analítica ! good, but it is also
> ! Universidad de Oviedo, 33006-Oviedo, Spain ! worse than bad, because
> ! e-mail:   victor at fluor.quimica.uniovi.es   ! mediocrity is not a grade,
> ! phone: +34-985-103491  fax: +34-985-103125 ! it is an attitude
> +--------------------------------------------+
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-- 
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
www.numis.northwestern.edu
Corrosion in 4D: MURI4D.numis.northwestern.edu
Co-Editor, Acta Cryst A
"Research is to see what everybody else has seen, and to think what nobody
else has thought"
Albert Szent-Gyorgi
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