Hello Naseem,
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.
There are multiple avenues you can take. The first is to search the
literature and databases (COD: http://www.crystallography.net and ICSD
if you have access to it http://www.fiz-karlsruhe.com/icsd_home.html),
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.
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.
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.
Trying to get more details on what you might be looking for is going to
be the first step either way.
Good luck,
Michael Sluydts
Naseem Hassan schreef op 4/07/2014 11:53:
Thank You All.
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.
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.
Best Regards
Naseem
On Fri, Jul 4, 2014 at 1:16 PM, Juan Manuel Perez Mato
<wmppe...@lg.ehu.es <mailto:wmppe...@lg.ehu.es>> wrote:
Please, learn some elementary crystallography in the International
year of crystallography.
regards,
J. Manuel Perez-Mato
Fac. Ciencia y Tecnologia,
Universidad del Pais Vasco, UPV
48080 BILBAO,
Spain
tel. +34 946012473 <tel:%2B34%20946012473>
fax. +34 946013500 <tel:%2B34%20946013500>
***************************************************
El 04/07/2014, a las 02:37, Naseem Hassan escribió:
Dear Sir,
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.
Thank you
Best Regards
Naseem Hassan
On Fri, Jul 4, 2014 at 1:22 AM, Peter Blaha
<pbl...@theochem.tuwien.ac.at
<mailto:pbl...@theochem.tuwien.ac.at>> wrote:
Without atomic positions one cannot create a structure.
Am 03.07.2014 19:46, schrieb Naseem Hassan:
Dear Wien2k experts
I am reporting this difficulty after going through
mailing list and
literature review. Kindly guide how can I generate
structure file with
the following information.
Compound Formula: V3S7Cl
Space Group: C mmm#65 Orthorhombic
lattice parameters: a=20.6 b=3.8, c=3.9
I need *general structure file* for this compound I will
try to remove
error associated with RMTs and other initializing
parameters by my self.
Alternatively,
If I select 3 atoms in the structure generation and I
insert all the
parameters as stated above then I just miss the position
of three atoms
in the structure file. In order to fill the positions I
checked the
wycoff psoitions from the Bilbao Crystallographic server
but I am unable
to understand which position should I give. *If this
approach is
correct* then kindly just *provide the positions* which I
can fill at
least ideal positions for this kind of space group so
that I can fill
and later on I will relax my structure to get actual
positons. Kindly do
guide.
Best Regards
Naseem Hassan
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TU Vienna
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Austria
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