<div dir="ltr"><div><div><div><div>Really appreciate last two responses. Thank you both of you Sir.<br><br></div><div>Everyone helped me on many occasions. I am grateful to all of you. <br></div></div><br></div>Best regards <br>
</div>Naseem<br></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Fri, Jul 4, 2014 at 3:04 PM, Michael Sluydts <span dir="ltr"><<a href="mailto:Michael.Sluydts@ugent.be" target="_blank">Michael.Sluydts@ugent.be</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<div>Hello Naseem,<br>
<br>
The problem you have is a lack of information. The spacegroup and
stoichiometry still give you freedom through wyckoff positions to
create a variety of structures.<br>
<br>
There are multiple avenues you can take. The first is to search
the literature and databases (COD: <a href="http://www.crystallography.net" target="_blank">http://www.crystallography.net</a>
and ICSD if you have access to it
<a href="http://www.fiz-karlsruhe.com/icsd_home.html" target="_blank">http://www.fiz-karlsruhe.com/icsd_home.html</a>), though I did not
immediately find anything of interest in COD. If you cannot find
the structure then it becomes a different problem, rather than
determining materials properties you will have to do structure
prediction.<br>
<br>
Structure prediction is a discipline in itself (literature
available) and can take a lot of time. If you know of similar
compounds you may be able to base yourself on them as a starting
point to reduce your search space, then try a few different
configurations for the atoms, optimize your cells and see what is
lowest in energy. <br>
<br>
Other more advanced methods are things like genetic algorithms
where you try different structures then combine them and gradually
converge to a candidate for the optimal structure. Software like
USPEX exists for this but I don't think it has been used with
wien2k, though interfacing with it should not be entirely
impossible.<br>
<br>
Trying to get more details on what you might be looking for is
going to be the first step either way.<br>
<br>
<br>
Good luck,<br>
<br>
Michael Sluydts<br>
<br>
<br>
<br>
Naseem Hassan schreef op 4/07/2014 11:53:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div>
<div>
<div>Thank You All.<br>
</div>
<br>
I benefited from all of you on mailing list. You are
absolutely right I should learn instead of spoon feeding. I
can understand fully that experts are already handling the
burden of below average questions. <br>
<br>
Inspite of all your recommendation I wish that someone
should suggest a road map of topics that leads to solution
of making new structure in WIEN2k. I see many emails on
mailing list that suggest the similar kind of problem of
making structure for a specific space group. I really wanted
to learn this but always lost in multiple topics. Many of
seniors to whom I know personally know can not solve this
problem. Just suggesting, that it will beneficial for
newcomers if someone can prepare a tutorial on this issue.
We sometimes do not work on compounds just because we cannot
make structure file in wien2k.<br>
<br>
</div>
Best Regards<br>
</div>
Naseem<br>
<div>
<div> <br>
</div>
</div>
</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Fri, Jul 4, 2014 at 1:16 PM, Juan
Manuel Perez Mato <span dir="ltr"><<a href="mailto:wmppemam@lg.ehu.es" target="_blank">wmppemam@lg.ehu.es</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="word-wrap:break-word">Please, learn some
elementary crystallography in the International year of
crystallography.
<div>
<br>
</div>
<div>regards,</div>
<div>
<div><span style="border-collapse:separate;color:rgb(0,0,0);font-family:Helvetica;font-size:medium;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">
<div>
<br>
</div>
<div>J. Manuel Perez-Mato<br>
Fac. Ciencia y Tecnologia,<br>
Universidad del Pais Vasco, UPV<br>
48080 BILBAO,<br>
Spain<br>
<br>
tel. <a href="tel:%2B34%20946012473" value="+34946012473" target="_blank">+34
946012473</a><br>
fax. <a href="tel:%2B34%20946013500" value="+34946013500" target="_blank">+34
946013500</a><br>
***************************************************<br>
</div>
<div><br>
</div>
</span></div>
<div>
<div>El 04/07/2014, a las 02:37, Naseem Hassan
escribió:</div>
<br>
<blockquote type="cite">
<div dir="ltr">
<div>Dear Sir,<br>
<br>
</div>
<div>Every space group has some ideal positions.
From little experience in the past, I believe on
selecting 3 atoms in the start of structure
generation and assigning positions for three
atoms will give the primitive cell for this
space group. In this primitive cell other
positions appear automatically by Wien2k. Does a
space group has not ideal positions ?. I need
ideal positions for three atoms and then I will
relax the structure to actual positions for this
compound. Modeling a material is possible
without experimental results. I am hopeful that
you will propose some kind of solution. <br>
<br>
</div>
<div>Thank you<br>
</div>
<div>Best Regards<br>
</div>
<div>Naseem Hassan<br>
</div>
<div><br>
<br>
</div>
</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Fri, Jul 4, 2014 at
1:22 AM, Peter Blaha <span dir="ltr"><<a href="mailto:pblaha@theochem.tuwien.ac.at" target="_blank">pblaha@theochem.tuwien.ac.at</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Without atomic
positions one cannot create a structure.<br>
<br>
Am 03.07.2014 19:46, schrieb Naseem Hassan:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Dear Wien2k experts<br>
<br>
I am reporting this difficulty after going
through mailing list and<br>
literature review. Kindly guide how can I
generate structure file with<br>
the following information.<br>
<br>
Compound Formula: V3S7Cl<br>
Space Group: C mmm#65
Orthorhombic<br>
lattice parameters: a=20.6
b=3.8, c=3.9<br>
<br>
I need *general structure file* for this
compound I will try to remove<br>
error associated with RMTs and other
initializing parameters by my self.<br>
<br>
Alternatively,<br>
<br>
If I select 3 atoms in the structure
generation and I insert all the<br>
parameters as stated above then I just miss
the position of three atoms<br>
in the structure file. In order to fill the
positions I checked the<br>
wycoff psoitions from the Bilbao
Crystallographic server but I am unable<br>
to understand which position should I give.
*If this approach is<br>
correct* then kindly just *provide the
positions* which I can fill at<br>
least ideal positions for this kind of space
group so that I can fill<br>
and later on I will relax my structure to
get actual positons. Kindly do<br>
guide.<br>
<br>
Best Regards<br>
Naseem Hassan<br>
<br>
<br>
<br>
<br>
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