[Wien] Guidance require for structure generation

Fri Jul 4 12:32:53 CEST 2014

Really appreciate last two responses. Thank you both of you Sir.

Everyone helped me on many occasions. I am grateful to all of you.

Best regards
Naseem

On Fri, Jul 4, 2014 at 3:04 PM, Michael Sluydts <Michael.Sluydts at ugent.be>
wrote:

>  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 <wmppemam at 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 <%2B34%20946012473>
>> fax. +34 946013500 <%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 <pblaha at 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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>>>>
>>> --
>>> Peter Blaha
>>> Inst.Materials Chemistry
>>> TU Vienna
>>> Getreidemarkt 9
>>> A-1060 Vienna
>>> Austria
>>> +43-1-5880115671
>>> _______________________________________________
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>>>
>>
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>>
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>
>
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