[CP2K-user] Cell Optimization for Copper.

[Travis]

Hi,

It's not too bad but can probably be better. You can check for convergence 
of the lattice parameter by increasing k-points, changing basis, changing 
cutoffs, tightening convergence criteria, etc. Different potentials will 
give different results - and will vary in quality across the periodic 
table. The warnings are due to features missing in CP2K when using Fermi 
smearing. They are safe to ignore. Converting a CIF file to XYZ loses 
symmetry operations, so you need to fill the unit cell. I usually convert 
from CIF to XYZ because sometimes CP2K struggles to read in CIFs and quits 
out.

-T


On Friday, August 16, 2019 at 7:48:13 AM UTC-3, Hasan Al-Mahayni wrote:
>
> I ran the files you posted. I get 3.651 Angstroms as a result in few 
> iterations, which is still far from 3.621. I don't know if that's ok, but I 
> get 11 warnings in my output file that I attached. Also, what is the 
> meaning to the fact that the XYZ file has 4 atoms of copper only?
>
> Thanks for your help,
> Hasan.
>
> On Wednesday, August 14, 2019 at 8:25:15 PM UTC-4, Hasan Al-Mahayni wrote:
>>
>> Hello all,
>>
>> I am fairly new to cp2k so I believe this issue is easily resolvable. My 
>> end goal is calculating adsorption energy of different molecules on copper 
>> surfaces (slab). However, the first step I need to do is optimize the cell 
>> parameters of copper(cell size). I know from materials project site that it 
>> is 3.62126 Angstroms. That is the configuration I start with and is 
>> attached by the name of "copper.xyz". The problem I am having is that 
>> when I run cell optimization on this (input file is "copper.inp"), I get 
>> the wrong results as the cell size shrinks (I get 3.4A). I think this is 
>> because of the vacuum between the copper cell and the simulation cell. My 
>> question is, what is the right way to set up the input file and especially 
>> the &CELL part. I started off by making the A B C cell size 10 A bigger 
>> than 3.62A, but that gives me the wrong result. If the A B C cell size is 
>> too small, I get an error saying geometry is wrong. Also, maybe GEO_OPT 
>> would be a more appropriate run type... I tried making supercell 2x2x2, 
>> 3x3x3, and 4x4x4 while keeping ABC cell size 10 A bigger every time, and 
>> the result gets closer to 3.62 but this method is not ideal as the system 
>> gets bigger and bigger and the calculation is more computationally 
>> expensive. Any ideas?
>>
>> Thanks,
>>
>> Hasan.
>>
>
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