[CP2K:968] PMF for butane rotation

[Teodoro Laino]

Ilya,

there was a bug for the extended lagrange metadynamics in case of  
periodic colvar (the torsion)..
So thanks for raising this problem..

Few hints and 1 complain ;-) :
(1) THIS POINT IS VERY IMPORTANT:  if units in the corresponding  
keyword in the webpage are not specified this means that
        you can only provide it in atomic units.
        In your case LAMBDA is 1.0 that means roughly 627.510 Kcal/ 
rad^2.. is this what you want????
(2) Nose is ok.. Personally I prefer the CVSR.. your system is anyway  
too small to correctly define a temperature..
       You may want to use a smaller timecon at least.. in your case  
the temperature is soon going over 3000K!!!!
(3) It is really appreciated when input files are attached instead of  
being embedded into the body mail..  thanks..

If you update cp2k  you will get:
(1) bug fix for the extended lagrangian for periodic colvar
(2) units have been added to LAMBDA
(the newest the best! sorry Nick for cribbing your motto ;-) )

Moreover in attachment you will find my corrections to your input file.
Thanks again for the bug reporting..

Teo
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On 23 Apr 2008, at 14:48, ilya wrote:

>
>
> Hi !!!
>
> I'm trying to perform a test metadynamics run to obtain free energy
> profile for butane C2-C3 torsion rotation.
> I've prepared an input according to examples, but when I execute the
> simulation the molecule blows up after a hundred of steps.
> Here is the input
>
> &FORCE_EVAL
>   METHOD QS
>   &DFT
>     &QS
>       METHOD AM1
>       &SE
>         ANALYTICAL_GRADIENTS T
>       &END
>     &END QS
>     &SCF
>       SCF_GUESS ATOMIC
>     &END SCF
>   &END DFT
>   &SUBSYS
>     &CELL
>       ABC 20.0 20.0 20.0
>       UNIT ANGSTROM
>       PERIODIC NONE
>     &END CELL
>     &COORD
>       C            1.59125586     0.41342479     0.14003727
>       C            0.32252829     1.16124839     0.52263341
>       C           -0.84910157     0.43265546    -0.11376540
>       C           -1.94048663     1.46412511    -0.50840178
>       H            1.52870579    -0.60735277     0.37898357
>       H            1.74514439     0.42933751    -0.91517059
>       H            2.40297038     0.84409489     0.68368432
>       H            0.30718345     1.26800062     1.63077856
>       H            0.42763214     2.20188061    -0.01524355
>       H           -0.68227576    -0.15483956    -1.02552216
>       H           -1.22868583    -0.36692588     0.50963056
>       H           -2.35282430     1.89592861     0.40350185
>       H           -1.56059968     2.32543646    -1.17180146
>       H           -2.80524537     1.06601703    -0.96111067
>     &END COORD
>     &COLVAR
>       &TORSION
>         ATOMS 1 2 3 4
>       &END TORSION
>     &END
>   &END SUBSYS
> &END FORCE_EVAL
> &GLOBAL
>   PROJECT_NAME BUTANE
>   RUN_TYPE MD
> &END GLOBAL
> &MOTION
>   &MD
>     ENSEMBLE NVT
>     STEPS 5000
>     TIMESTEP 0.5
>     TEMPERATURE 300.0
>     &THERMOSTAT
>       &NOSE
>       &END NOSE
>     &END THERMOSTAT
>   &END MD
>   &PRINT
>     &VELOCITIES OFF
>     &END
>     &TRAJECTORY
>     &END
>   &END
>   &FREE_ENERGY
>     &METADYN
>       DO_HILLS
>       LAGRANGE
>       WW 0.001
>       &METAVAR
>         LAMBDA 1.0
>         MASS 10.0
>         SCALE 0.1
>         COLVAR 1
>       &END METAVAR
>       &PRINT
>         &COLVAR
>           &EACH
>             METADYNAMICS 100
>           &END
>         &END COLVAR
>         &HILLS
>           &EACH
>             METADYNAMICS 100
>           &END
>         &END HILLS
>       &END
>     &END METADYN
>   &END FREE_ENERGY
> &END MOTION
>
> Is it possible to obtain a detailed description of input somewhere
> (more then in input manual) or could someone make needed corrections
> in my input or to explain what am I doing incorrect (should I
> experiment with metadynamics parameters, add walls or something
> else?). It would be great.
>
> Thanks a lot.
> Best regards,
> Ilya.
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