[Pw_forum] Open shell system calculations

[stefano de gironcoli]

* Martyna-Tuckerman option for assume_isolated variable in the &System 
namelist.

stefano


On 10/08/2017 09:00, stefano de gironcoli wrote:
> I think spin unpolarized calculations in that case miss a large 
> exchange correlation contribution coming from spin alignment.
> Isolated Mn2+ should have total magnetization equal to 5 (i think). 
> You can set this from input. Or you can just let the code find the 
> minimum by itself.
>
> you can use martina-tuckerman option to decouple periodic images.
> It's very important for charged systems.
> That should reduce the size of supercell needed to have stable numbers.
>
> stefano
>
>
> On 10/08/2017 08:50, Iryna Zaporozhets wrote:
>> I have a single Mn2+  ion in the isolated system with vacuum between 
>> periodic images. Spin-unpolarized calculations run without any errors 
>> so I wonder whether spin-unpolarized calculations produce any useful 
>> results.
>>
>> Best, Iryna Zaporozhets
>>
>> 2017-08-09 23:39 GMT-07:00 stefano de gironcoli <degironc at sissa.it 
>> <mailto:degironc at sissa.it>>:
>>
>>     depends on your system, is it magnetic ?
>>     metallic aluminum or copper have spin compensated densities and
>>     you can use nspin=1.
>>     nickel or iron are magnetic and nspin=2 is needed.
>>     stefano
>>
>>
>>     On 10/08/2017 08:29, Iryna Zaporozhets wrote:
>>>     Dear PW community,
>>>
>>>     I am working with an open-shell system which requires a lot of
>>>     computational efforts. Is it possible to use other options than
>>>     spin-polarized calculations (nspin = 2) to reduce computational
>>>     cost, for example, restricted open-shell  DFT?  Is there any
>>>     physical meaning to the results obtained with
>>>     spin-unpolarized (nspin = 1) calculations in case of the
>>>     open-shell system?
>>>
>>>     Thank you,
>>>     Iryna Zaporozhets,
>>>     Master student in Chemistry
>>>     Kharkiv National University, Ukraine
>>>
>>>
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>>
>>
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