[CP2K:419] grid settings

[Teodoro Laino]

Ciao Nick,

to get the exact number can be really tricky.. you need to have a  
pretty good knowledge of the GPW and
(specifically for your input) GAPW method.
Anyway I will just drive you shortly in the right direction for your  
input file:

>
> &FORCE_EVAL
>   METHOD Quickstep
>   &DFT
>     &SCF
>       SCF_GUESS ATOMIC
>     &END SCF
>     &XC
>       &XC_FUNCTIONAL BLYP
>       &END XC_FUNCTIONAL
>     &END XC
>     &QS
>       METHOD GAPW
>     &END QS

>     &POISSON
>       POISSON_SOLVER ANALYTIC
>       PERIODIC NONE
>     &END POISSON

ANALYTIC is ok though you may need a much  larger cell to efficiently  
decouple the periodic images.. Try instead:
     &POISSON
       POISSON_SOLVER MT
       PERIODIC NONE
     &END POISSON
for more info see the Martyna & Tuckermann related paper.

>   &END DFT
>   &SUBSYS
>     &CELL
>       ABC 7.0 7.0 7.0
>       PERIODIC NONE
>       UNITS ANGSTROM
>     &END CELL
>     &COORD
>       H 0.0 0.0 0.85
>       H 0.0 0.0 0.0
>     &END COORD
>     &KIND H
>       BASIS_SET 6-31G*
>       POTENTIAL ALL
>     &END KIND
>   &END SUBSYS
> &END FORCE_EVAL
> &GLOBAL
>   PROJECT H2-cp2k
>   RUN_TYPE ENERGY_FORCE
> &END GLOBAL
>

This is the energy you get:
   Total energy:                                                
-1.15974372512219
And Gamess:
gamess =                                                        
-1.1597712381

you may for sure tune better GAPW (see the full bunch of GAPW  
keywords) to get a better agreement, though 3*10^-5 Hartree is not  
such a bad number.

teo