[CP2K-user] Cell Optimization for Copper.

[Hasan Al-Mahayni]

Hi,

Thanks for your reply, I tried both methods. 
1) For the Kpoint method, I get the following error: "GEOMETRY wrong or 
EMAX_SPLINE too small!"
2)For MULTIPLE_UNIT_CELL what should I write after it (the "X Y Z" 
section)? Should I start with 2 2 2? Also, do I put the same thing in both 
TOPOLOGY and CELL section?

Thanks,
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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