[CP2K:10507] Huge difference in adsorption energies between CP2K and VASP with PBE

[Sharma SRK Chaitanya Yamijala]

Dear Prof. Hutter,

Thanks. I will try the BSSE correction with CP2K. Regarding k-point 
sampling, in both the softwares, I have used Gamma point only. Could you 
please elobarate your point on "size of basis sets" here? I don't know how 
should I compare VASP basis (plane waves) with CP2K (both PW and 
Gaussians)? I have converged the CUTOFFs in both the cases such that the 
energy differences are < 1 meV. 

Also, yesterday, I have performed similar calculations with FHIAims and I 
have obtained the adsorption energy (withOUT dispersion and BSSE 
corrections) as 0.412 eV which is again closer to the VASP result and to 
the result in the reference.

Seeking your advice.

Thanks,
Sincerely,
Sharma.

On Thursday, July 12, 2018 at 12:11:59 AM UTC-7, jgh wrote:
>
> Hi 
>
> my first guess: you didn't calculate the BSSE correction. 
>
> other possible contributions: size of basis sets 
>                               k-point sampling 
>
> 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 
> <javascript:> 
> Winterthurerstrasse 190 
> CH-8057 Zürich, Switzerland 
> --------------------------------------------------------------- 
>
> -----cp... at googlegroups.com <javascript:> wrote: ----- 
> To: cp... at googlegroups.com <javascript:> 
> From: "Sharma SRK Chaitanya Yamijala" 
> Sent by: cp... at googlegroups.com <javascript:> 
> Date: 07/12/2018 01:48AM 
> Subject: [CP2K:10507] Huge difference in adsorption energies between CP2K 
> and VASP with PBE 
>
> Dear CP2K members, 
>
> I am calculating the adsorption energies of CO on ZnO (4x4-slab with 4 
> layers of ZnO(10-10) surface). The adsorption energy obtained from VASP is 
> ~ 0.3 eV (without dispersion) and it is ~ 0.45 eV (with dispersion). 
> However, when calculating the same system with CP2K (geometry is 
> re-optimized), I am obtaining the energies 0.688 eV and 0.863 eV for 
> without and with dispersion correction, respectively. 
>
> The literature value is close to the VASP result. Here is the reference 
> (kindly, see Table 2, C-down, 2x1 cell, Full). 
>
> B Meyer and D Marx 2003 J. Phys.: Condens. Matter 15 L89 
> http://iopscience.iop.org/article/10.1088/0953-8984/15/2/112/pdf 
>
> Could anyone give an advice on why there is such a discrepancy in the 
> adsorption energies irrespective of using the same functional? 
>
> I am attaching the geometry and the input file for your reference. 
>
> Thanks, 
> Sharma. 
>
> -------------------------------------------------------------------- 
> SRK Chaitanya Sharma, Yamijala. 
> http://www.bmwong-group.com/group-members/ 
>
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> [attachment "1CO_on_opt_4x4_slab.xyz" removed by Jürg Hutter/at/UZH] 
> [attachment "zno_bulk.inp" removed by Jürg Hutter/at/UZH] 
>
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