[CP2K:7053] Re: how to choose the frequency at which stress is calculated

S Ling lingsa... at gmail.com
Thu Oct 15 00:47:09 CEST 2015


Hi Luis,

I seem to remember there is no analytical stress tensor implemented for
meta-GGAs in CP2K because they use laplacian of the density, see:

https://groups.google.com/d/msg/cp2k/V5l4_iUORkY/WuQOQGrwAQAJ

In addition, the stress tensor from MD and single point energy calculations
will be different, see earlier post by Prof Hutter:

https://groups.google.com/d/msg/cp2k/rifbK2sdjJ4/O3nUipT0M8EJ

If you decide to run the numerical stress tensor calculations, please keep
in mind that you will need to use tighter convergence criteria (e.g.
plane-wave cutoff, energy, force).

I believe you will be able to find more useful information if you search in
the mailing list.

SL




On 14 October 2015 at 21:54, Luis Ruiz Pestana <lar... at lbl.gov> wrote:

> Thanks Matt.
>
> It would definitely be useful to implement a way in cp2k to calculate
> stresses when using metaGGA's (either through the analytical calculation or
> indirectly through the REFTRAJ ensemble using the numerical stress
> calculation). Let me know if you get it done any time soon, it would be a
> life saver!
>
> I really like cp2k and I highly recommend it to other users but in the
> current state I might be forced to change software to simulate systems with
> mGGA's.
>
> Best,
> Luis
>
> On Wed, Oct 14, 2015 at 1:35 PM, Matt W <MattWa... at gmail.com> wrote:
>
>> Hi Luis,
>>
>> seems like this might not be doable at the moment then, maybe only
>> energy-force. Sorry if the suggestion was bad. I'd think it would be easy
>> to add the extra ability to calculate stress tensor too, I'll try and have
>> a look, but not sure I'll have time for a bit.
>>
>> Matt
>>
>>
>> On Wednesday, October 14, 2015 at 5:27:04 PM UTC+1, lar... at lbl.gov wrote:
>>>
>>> Hi Matt,
>>>
>>> I have been trying to use REFTRAJ to calculate the stress on some frames
>>> from a trajectory that I already ran but I don't seem to get it to work.
>>> The simulation in the REFTRAJ ensemble runs fine but the outputs are zero
>>> for the stress and other quantities in the *.ener file. I have attached
>>> here the input file as well as the outputs for energy and stress. I am not
>>> sure what I'm doing wrong so any pointer would be highly appreciated.
>>> Thanks in advance for your help!
>>>
>>> Best,
>>> Luis
>>>
>>>
>>>
>>>
>>> On Sunday, September 13, 2015 at 5:53:08 AM UTC-7, Matt W wrote:
>>>>
>>>> Hi,
>>>>
>>>> the simplest way might be to post process - use the REFTRAJ ensemble in
>>>> the MD to rerun over the frames you like. The overhead of having to redo
>>>> the SCF from not quite as good a guess should be negligible.
>>>>
>>>> Matt
>>>>
>>>> On Friday, September 11, 2015 at 7:47:06 PM UTC+1, lar... at lbl.gov
>>>> wrote:
>>>>>
>>>>> Dear team,
>>>>>
>>>>> I was wondering if there is any available setting in cp2k to set the
>>>>> frequency at which the stress is calculated in an AIMD simulation. I am
>>>>> currently using metaGGAs in my simulations and because the only way of
>>>>> calculating the pressure is numerically for this type of xc functionals the
>>>>> MD simulations are painfully slow. If there would be a way to not perform
>>>>> the numerical stress calculation every step that would make them
>>>>> manageable. Btw, just changing how often it's printed doesn't change
>>>>> anything. Thanks in advance!
>>>>>
>>>>> Best,
>>>>> Luis
>>>>>
>>>> --
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>
>
>
> --
> Luis A. Ruiz Pestana, PhD
> Chemist Postdoctoral Fellow
> Lawrence Berkeley National Laboratory & UC Berkeley
> Berkeley, CA 94720
> Site: personal website <http://luisruiz2015.wix.com/personal>
>
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