CP2K energy very different from Gaussian03

[Matt W]

Hi,

you certainly should get a similar number for the observable reaction 
energy Fe + S -> FeS. 

But the energies of the individual species will be different. Potentially 
totally different if using different pseudopotentials. So just looking at 
the Fe atom energy is not a good idea.

On an actual CP2K note your basis set is too small - change SZV to DZVP for 
something OK. 

As David T says, best to compare like with like where possible, PADE 
functional in CP2K is LDA, so probably like SVWN keywords for exchange 
correlation in Gaussian for comparison.

Matt

On Monday, September 5, 2016 at 6:03:07 PM UTC+1, Megha Anand wrote:
>
> Dear All,
>
> I am pretty new to CP2K and still learning the basics of the program. I 
> want to get the energy of the energy of the reaction: Fe(g) + S(g) -> 
> FeS(g). To begin with, I simply did single point calculation of iron atom 
> using Gaussian03 and CP2K. Browsing through the previous posts, I figured 
> out that the ECP basis sets used by most quantum chemists cannot be used in 
> CP2K. Even if I use different level of theory and basis sets across the two 
> programs, I would anticipate roughly similar energies if not exactly same. 
> I used basis set B3LYP/SDD in Gaussian03 and SZV-MOLOPT-SR-GTH in CP2K. The 
> energies I get from Gaussian is: -123.85372 while in CP2K: 
> -19.96605887771384. Even if the two programs results in two spin states I 
> would not expect such large different. 
>
> I do not know what I am doing wrong. Any help will be greatly appreciated. 
> I have included the input below. Apart from these, I have few more general 
> questions:
>
> (a) Is there any recommended combination of pseudopotential and basis set 
> for complex compounds containing metal iron. There are also: carbon, 
> oxygen, sulfur, and nitrogen in the system.
>
> (b) Should I use GPW or do all electron calculation using GAPW. I would 
> have used ECP basis set, if I had to use Gaussian03. But I am not sure what 
> is right way proceed with CP2K.
>
> (c) Any suggestion for the functional available in CP2K for studying iron 
> complexes of high spin multiplicity. 
>
> (d) I saw ECP_POTENTIALS file on CP2K Github, is it possible to use ECPs 
> like SDD, LANL2DZ, etc. in CP2K.
>
>
> Here is my CP2K input:
>
> &GLOBAL
>
>   PROJECT Fe
>
>   RUN_TYPE ENERGY
>
>   PRINT_LEVEL MEDIUM
>
>   WALLTIME 86400
>
> &END GLOBAL
>
>
> &FORCE_EVAL
>
>   METHOD Quickstep
>
>   &DFT
>
>     BASIS_SET_FILE_NAME /share/apps/cp2k/cp2k/tests/QS/BASIS_MOLOPT
>
>     POTENTIAL_FILE_NAME /share/apps/cp2k/cp2k/tests/QS/GTH_POTENTIALS
>
>     CHARGE 0
>
>     MULTIPLICITY 5
>
>     UKS T
>
>
>     &MGRID
>
>       CUTOFF 400
>
>       REL_CUTOFF 60
>
>     &END MGRID
>
>
>     &QS
>
>       METHOD GPW
>
>       EPS_DEFAULT 1.0E-12
>
>     &END QS
>
>
>     &SCF
>
>       MAX_SCF 500
>
>       &OUTER_SCF
>
>         EPS_SCF 1.0E-6
>
>         MAX_SCF 60
>
>       &END OUTER_SCF
>
>     &END SCF
>
>
>     &POISSON
>
>       PERIODIC NONE
>
>       PSOLVER WAVELET
>
>     &END POISSON
>
>
>
>     &XC
>
>       &XC_FUNCTIONAL PADE
>
>       &END XC_FUNCTIONAL
>
>     &END XC
>
>
>   &END DFT
>
>
>   &SUBSYS
>
>     &CELL
>
>       ABC 7.00 7.00 7.00
>
>       PERIODIC NONE
>
>     &END CELL
>
>
>     &COORD
>
>       Fe    0.0000    0.0000    0.0000
>
>     &END COORD
>
>
>     &KIND Fe
>
>       BASIS_SET SZV-MOLOPT-SR-GTH
>
>       POTENTIAL GTH-PADE-q8
>
>     &END KIND
>
>   &END SUBSYS
>
> &END FORCE_EVAL
>
>
>
> Thanks,
>
> Megha
>
>
>
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