[CP2K:315] Minimization error with CG

Teodoro Laino teodor... at gmail.com
Fri Oct 5 16:38:06 CEST 2007


Luca,
The error you get with CG means that gradients are too large..
Rescaling the forces may help.. have a look at:

http://cp2k.berlios.de/input/ 
InputReference~__ROOT__~FORCE_EVAL~RESCALE_FORCES.html

or just starting from a geometry that has been annihilated with MD..

Anyway the very large forces may be due to your input file.
There are quite several things wrong in it:

1) Important: CONSTRAINTS at the moment DO NOT work with the geometry  
optimizer..
2)
>
>
> &FORCE_EVAL
>  METHOD FIST
>
>  &MM
>    &FORCEFIELD
>      PARM_FILE_NAME  ./par_amber2charmm.inp
>      PARMTYPE   CHM
>      EI_SCALE14 0.8333
>      VDW_SCALE14 1.0
>      &SPLINE
>        UNIQUE_SPLINE T
>        EMAX_SPLINE 0.5
>      &END SPLINE
>    &END FORCEFIELD
>
You're using just 1 spline.. so the spline generation cannot be slow  
(as you said).. If you use the full set of spline than.. yes.. it
could be slow...

3) You're not using any kind of electrostatic (EWALD_TYPE NONE)!! is  
this really what you want??????????
      Periodic NONE is not supported for MM run..  all MM run can be  
performed only in full periodicity (at the moment)...
>    &POISSON
>      &EWALD
>        EWALD_TYPE NONE
>        ALPHA 0.44
>        GMAX   64
>        O_SPLINE 6
>      &END EWALD
>      PERIODIC NONE
>    &END POISSON
>
4) PERIODIC NONE has no sense since you cannot do calculations that  
are not periodic with MM..
>     &CELL
>       ABC  57.000 60.0 53.000
>       UNIT ANGSTROM
>       PERIODIC NONE
>     &END CELL

Anyway I will look into the segfault (this could be due to the fact  
that SAVE_MEM was never tested for GEO_OPT)..
Teo



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