[CP2K-user] [CP2K:17662] Re: CP2K Cell Boundary Coordinates

Dev Kumar qknots4 at gmail.com
Tue Sep 13 14:04:54 UTC 2022

Thanks for responding. Thats standard steps we use in LAMMPS MD simulations 
also. I will try it out. 

On Tuesday, September 13, 2022 at 9:49:29 AM UTC-4 mattwa... at gmail.com 

> Well before you run NPT you need to check that you can converge the 
> electron structure and that there are no large forces present in the system.
> As for any MD I'd suggest a typical workflow would be at least a rough 
> geometry optimization. Then NVT then switch to NPT.
> NPT might need rather tight settings to have a well converged stress 
> tensor.
> Matt
> On Tuesday, 13 September 2022 at 14:23:57 UTC+1 qkn... at gmail.com wrote:
>> HI Matt, 
>> Thanks for your reply. I attached the POSCAR. I am new to cp2k and I 
>> assumed that cp2k is taking the angles of the box 90 degrees and cubic. 
>> This is just my lack of knowledge. This is cubic fcc cell, I can 
>> give ALPHA_BETA_GAMMA 90.00000000 90.00000000  90.00000000   SYMMETRY CUBIC 
>> inside cell. I will try that out. Although I will still need to make sure 
>> cp2k taking all the atoms inside the boundary. I may need to leave some 
>> vacuum sometimes, so I should be able to manipulate the box size. Please 
>> let me know you comments. 
>> When I look at the output position file it does look like its printing 
>> out from the initial position I started with, but becomes mushy after few 
>> steps of geometry optimization. 
>> On Tuesday, September 13, 2022 at 8:40:40 AM UTC-4 mattwa... at gmail.com 
>> wrote:
>>> I'm afraid I can't remember all Lammps' conventions - it would also 
>>> depend on system of units used in the data file etc
>>> Can you get ovito to also output a PDB or POSCAR or something you can 
>>> check against.
>>> Also, If you are running DFT you will want something closer to a cubic 
>>> cell if possible - and it might need to be quite large if your allow is 
>>> metallic...
>>> Matt
>>> On Monday, 12 September 2022 at 15:28:19 UTC+1 qkn... at gmail.com wrote:
>>>> Hi Experts, 
>>>> I am new cp2k user. I am trying to simulate a MD simulation on a 
>>>> metallic alloy and it keeps failing to start a NPT MD. I have a question 
>>>> about the structure boundaries in CP2K. I created the initial box in lammps 
>>>> and visualizing in ovito. Below are the box sizes. Am I converting it 
>>>> correctly for the cp2k simulation. 
>>>> *# LAMMPS data file written by OVITO*
>>>> 208 atoms
>>>> 3 atom types
>>>> -0.104644 20.6326618 xlo xhi
>>>> -19.8380928 19.8555032 ylo yhi
>>>> -0.0701645 2.082567 zlo zhi
>>>> *! CP2K Format*
>>>>  &CELL
>>>>       A   21.4280004501         0.0000000000         0.0000000000
>>>>       B   0.0000000000         42.9860000610         0.0000000000
>>>>       C   0.0000000000         0.0000000000        4.2329998016
>>>>       PERIODIC  XYZ 
>>>>     &END CELL
>>>>     &TOPOLOGY
>>>>       COORD_FILE_NAME AlCuMg.xyz
>>>>     &END
>>>> Thanks
>>>> Dev Kumar
>>>> Brown University
>>>> Providence, RI 

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