[CP2K:8891] geometry optimization for graphite

[Chenxing Yang]

Hi,

Thank you very much for the answer. 

Is k-points also the reason why I got incorrect distance between atoms and 
layers? How can I fix it? I tried adding KOINTS section in the DFT section, 
but it gives me following error message: "WFN based interpolation method 
not possible for kpoints."

Thank you very much!

Chenxing


Hi 
>
> my guess is, that you see the effect of incomplete sampling of 
> the Brillouin zone. By using different supercells you get 
> different back folding of the reciprocal cell. It is like using 
> more or less appropriate k-points. 
>
> regards 
>
> Juerg Hutter 
> -------------------------------------------------------------- 
> Juerg Hutter                         Phone : ++41 44 635 4491 
> Institut für Chemie C                FAX   : ++41 44 635 6838 
> Universität Zürich                   E-mail: hut... at chem.uzh.ch 
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> Winterthurerstrasse 190 
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> --------------------------------------------------------------- 
>
> -----cp... at googlegroups.com <javascript:> wrote: -----To: cp2k <
> cp... at googlegroups.com <javascript:>> 
> From: Chenxing Yang 
> Sent by: cp... at googlegroups.com <javascript:> 
> Date: 04/01/2017 05:21AM 
> Subject: [CP2K:8891] geometry optimization for graphite 
>
> Dear All, 
> I have run some simulations of geometry optimization for graphite with 
> OPT-PBE using CP2K 4.1, and I have some problem on reproducing the correct 
> crystalline structure of graphite. 
> For some reason, the bond length is slightly overestimated (1.448 Å), and 
> inter-layer distance is underestimated (2.756 Å), where experiment results 
> are 1.421 Å and 3.33 Å. It seems those 2 distances can be very well 
> reproduced using OPT-PBE in the literature. Could you please help me to 
> check if something is wrong in the input file? 
> Another problem I encountered is, if I simulate in a 3*3*3 supercell, the 
> atoms is located same position of atoms in the adjacent layer, instead of 
> centre of hexagon, but it is fine if the supercell is set as 2*2*2 and 
> 4*4*4.  
> Here is my input file attached. Thank you very much! 
> Kind regards, 
> Chenxing Yang 
>
>
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> [attachment "graphite.inp" removed by Jürg Hutter/at/UZH] 
>
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