[ase-users] GULP calculator in ASE with periodic boundary conditions

[James Aston]

Hi,

Thanks for the response. My output for my periodic crystal has 'Final  
internal derivatives' in units of eV instead. I have tried to change  
the output of this by searching for different gulp keywords but  
couldn't find any solutions. Do you think it would wise for me to  
proceed by parsing the gulp output file for the internal derivatives  
and using this information for my phonon calculations?

Best wishes,
James

Quoting Ask Hjorth Larsen <asklarsen at gmail.com> on Tue, 16 Jan 2018  
18:41:48 +0100:

> Hi,
>
> 2018-01-16 18:05 GMT+01:00 James Aston via ase-users
> <ase-users at listserv.fysik.dtu.dk>:
>> Hello everyone,
>>
>> I am a PhD student at the University of Edinburgh and a new user of ASE. I
>> am having trouble using the GULP calculator to determine the forces and
>> phonon dispersion of a periodic crystal structure.
>>
>> I am currently trying to use the 8-Si example given here
>> (https://github.com/atztogo/phonopy/blob/master/example/ase/8Si-phonon.py).
>> I have set the calculator to calc = GULP(library='tersoff.lib',
>> keywords="conp, gradient, fractional, nosymmetry").
>
> (The examples in ASE use "conp gradient ...." without commas.  I infer
> that probably it is supposed to work anyway though.)
>
>>
>> The code runs when periodic boundary conditions are set to false, albeit
>> with negative phonon frequencies. When I set periodic boundary conditions to
>> true I get an error from get_forces():
>>
>> 'ase.calculators.calculator.PropertyNotImplementedError: forces not present
>> in this calculation'
>>
>> Does anyone know how to fix this? Thank you in advance.
>
> Probably the forces are printed differently so the parser does not find them.
>
> The parser looks only for "Final Cartesian derivatives".  Does your
> output have that?
>
> Best regards
> Ask
>
>>
>> Best wishes,
>> James
>>
>>
>> --
>> The University of Edinburgh is a charitable body, registered in
>> Scotland, with registration number SC005336.
>>
>>
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>
>



-- 
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.