CP2K energy very different from Gaussian03

[Megha Anand]

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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