[CP2K:7816] Cell optimization : z direction constraint

[S Ling]

Hi

You can download the source code into your own directory and create another
executable for your own use. This will not affect other people. You can use
exactly the same ARCH file to compile the modified code.

SL


On 30 May 2016 at 09:36, ashish dabral <ashishd... at gmail.com> wrote:

> Thanks for your input S Ling. I have a lot of servers with cp2k compiled
> for them. It is not reasonable to do it again just to control the z height
> as a lot of other people use the same
> code. If recompilation is the only way then I would rather go for an
> increased vacuum.
>
> Thanks
>
> On Friday, 27 May 2016 18:31:10 UTC+2, S Ling wrote:
>>
>> Hi
>>
>> If you have vacuum in your model, and you want to keep z fixed during
>> cell_opt, then you need to modify the code and recompile it, see
>> https://groups.google.com/d/msg/cp2k/XescBifa_ik/SHSnf1G5QdgJ for more
>> details.
>>
>> Basically, you need to go to your CP2K source code, find the
>> cell_opt_utils.F file (located in $CP2K/cp2k/src/motion directory), go to
>> the end of the file and add "gradient(6) = 0.0_dp" below "gradient =
>> -gradient". Then you will need to recompile the code and run your
>> calculation with the new executable.
>>
>> SL
>>
>>
>>
>> On 27 May 2016 at 16:54, ashish dabral <ashis... at gmail.com> wrote:
>>
>>> Hi,
>>>
>>> Can someone explain to me how I can do a Cell optimization with a fixed
>>> z direction(height) while everything else (including atomic coordinates)
>>> can change? I usually take 20A as the z height (supercell z vector
>>> length) for my 2d systems to isolate image cell interactions but apparently
>>> some structures are contracting in the z direction and reaching bulk
>>> state after 200 iterations, which is really time consuming. I want the
>>> system
>>> to move to prevent any stress but I do not want contraction because it
>>> does not remain 2d anymore.
>>>
>>> Also, If I fix the vertical height, will it be right? I mean if the
>>> original system with that vertical height want to contract then it has
>>> interactions
>>> with the image cell. If I fix the height then I would still have the
>>> interactions with the image cell above but will not see it in optimized
>>> structure.
>>> Will this be right approach?
>>>
>>>
>>> Thanks
>>>
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>>
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