[CP2K:1122] Re: %METAVAR%TEMP_TOL Vs. %METAVAR%WALL

[Teodoro Laino]

Francesco,

if you don't put TEMP_TOL no temperature rescaling is performed over  
the collective variables.
If you put TEMP_TOL the temperature of the COLVAR is rescaled  
according the tolerance.
Now let me comment your message:

>> I've had some problems to
>> add the walls on the colvar, since I found difficult to turn them on.
walls are automatically turned on if you ask for them in the input  
file (if not provide an
input, fast enough to be run (this usually means not more than few  
SECONDS) for
debugging. The input file you provided merged in your message does  
not show any
problem to me (as long as I was patience enough to run it)).

>>
>> In principle, there is a wall_minus at -4 and a wall_plus at +4,
>> colvar is around -2 at
>> the beginning of the simulation. To test that the walls were  
>> active, I
>> did a very simple
>> test.  I put wall_minus at +4 and wall_plus at -4.
>> This way, at the first MD step I should find crazy potential energy.
Very laudable effort.. BUT this is not the case since velocities are  
rescaled in between
the velocity verlet.. so if you have temp_tol on you will never see  
the potential going crazy
because velocities of the particles are rescaled to the value you  
requested.

>> However, if I set any TEMP_TOL (from 0.0 to 1.E10) for the METAVAR
>> %ROOT%MOTION%FREE_ENERGY%METADYN%TEMP_TOL
>> nothing happens, the potential energy at the first MD step is the
>> total scf energy.
See above.

>>
>> As I simply remove the TEMP_TOL for the METAVAR from the input, the
>> potential energy at
>> the first MD step, as expected, goes crazy because of the walls.
See above.

>> In short, it seems to me that the walls are active if TEMP_TOL on the
>> METAVAR is not
>> included in the input.
wrong conclusion. WALLS and TEMP_TOL have two independent setup.

>> Is it that normal ? Am I missing something of
>> the story ?
If you think how MD works it will be everything clear to you  
(consider that velocities are
rescaled immediately after the integration).

cheers,
Teo

>>
>> Here is the input for a fast (less then 5 mins on a Xeon quadcore)
>> test.
>> Thanks,
>> francesco
>>
>> &MOTION
>>    &MD
>>      COMVEL_TOL 1.0E-08
>>      ANGVEL_ZERO T
>>      ENSEMBLE NVT
>>      TEMPERATURE 300.0
>>      STEPS 10
>>      TIMESTEP 0.5
>>      &THERMOSTAT
>>         TYPE NOSE
>>         REGION GLOBAL
>>         &NOSE
>>         &END NOSE
>>      &END THERMOSTAT
>>    &END MD
>>    &FREE_ENERGY
>>      METHOD METADYN
>>      &METADYN
>>        DO_HILLS F
>>        LAGRANGE T
>>        TEMPERATURE 300.0
>>        TEMP_TOL 80.0
>>        WW 0.0005
>>        &METAVAR
>>          MASS 10.0
>>          SCALE 0.15
>>          LAMBDA 0.5
>>          COLVAR 1
>>          &WALL
>>            TYPE QUADRATIC
>>            POSITION 4.0
>>            &QUADRATIC
>>              K 100.0
>>              DIRECTION WALL_MINUS
>>            &END QUADRATIC
>>          &END WALL
>>          &WALL
>>            TYPE QUADRATIC
>>            POSITION -4.0
>>            &QUADRATIC
>>              K 100.0
>>              DIRECTION WALL_PLUS
>>            &END QUADRATIC
>>          &END WALL
>>        &END METAVAR
>>        &PRINT
>>          &COLVAR
>>            FILENAME =colvar
>>          &END COLVAR
>>        &END PRINT
>>      &END METADYN
>>    &END FREE_ENERGY
>>    &PRINT
>>      &TRAJECTORY
>>        &EACH
>>          MD 2
>>        &END EACH
>>      &END TRAJECTORY
>>      &VELOCITIES
>>        &EACH
>>          MD 2
>>        &END EACH
>>      &END VELOCITIES
>>      &RESTART
>>        &EACH
>>          MD 10
>>        &END EACH
>>      &END RESTART
>>    &END PRINT
>>    &GEO_OPT
>>    &END GEO_OPT
>> &END MOTION
>> &FORCE_EVAL
>>    METHOD Quickstep
>>    &DFT
>>       &POISSON
>>           POISSON_SOLVER WAVELET
>>           PERIODIC NONE
>>       &END POISSON
>>       BASIS_SET_FILE_NAME BASIS_AU
>>       POTENTIAL_FILE_NAME POT_AU
>>       CHARGE -1
>>      &MGRID
>>        CUTOFF 280
>>      &END MGRID
>>      &QS
>>        EXTRAPOLATION ASPC
>>        EXTRAPOLATION_ORDER 3
>>      &END QS
>>      &SCF
>>        EPS_SCF 1.0E-6
>>        SCF_GUESS ATOMIC
>>        &PRINT
>>          &RESTART OFF
>>          &END
>>        &END PRINT
>>        &OT
>>          MINIMIZER DIIS
>>          N_DIIS 7
>>          PRECONDITIONER FULL_SINGLE_INVERSE
>>        &END OT
>>        &OUTER_SCF
>>          EPS_SCF 1.0E-4
>>          MAX_SCF 4
>>        &END OUTER_SCF
>>      &END SCF
>>      &XC
>>        &XC_FUNCTIONAL BLYP
>>        &END XC_FUNCTIONAL
>>      &END XC
>>    &END DFT
>>    &SUBSYS
>>      &CELL
>>        ABC 12.0 12.0 12.0
>>        UNIT ANGSTROM
>>        PERIODIC NONE
>>      &END CELL
>>      &COORD
>>   C      6.21755040790000        6.27945039380000
>> 5.87094203540000
>>   Cl     8.06896049700000        6.19655506190000
>> 6.18039982360000
>>   Cl     3.14468329460000        5.68026996200000
>> 5.90402508870000
>>   H      5.81537329980000        6.79388677010000
>> 6.75597666210000
>>   H      5.90571792570000        5.23287421340000
>> 5.79791183930000
>>   H      6.05556449220000        6.86392371860000
>> 4.95315969410000
>>      &END COORD
>>      &VELOCITY
>>   -2.214634000000000E-004 -2.388178000000000E-004
>> -4.611093000000000E-004
>>   -3.043920000000000E-005  6.815900000000000E-005
>> 1.200276000000000E-004
>>    1.033677000000000E-004  4.250750000000000E-005
>> 6.534730000000000E-005
>>   -3.199348000000000E-004 -1.111403800000000E-003
>> -3.637730000000000E-005
>>    3.678017000000000E-004  2.676782000000000E-004
>> -7.108579000000001E-004
>>    2.604120000000000E-005 -2.029183000000000E-004
>> -2.782362000000000E-004
>>      &END VELOCITY
>>      &KIND H
>>        BASIS_SET DZVP-GTH-BLYP
>>        POTENTIAL GTH-BLYP-q1
>>      &END KIND
>>      &KIND C
>>        BASIS_SET DZVP-GTH-BLYP
>>        POTENTIAL GTH-BLYP-q4
>>      &END KIND
>>      &KIND Cl
>>        BASIS_SET DZVP-GTH-BLYP
>>        POTENTIAL GTH-BLYP-q7
>>      &END KIND
>>      &COLVAR
>>        &DISTANCE_DIFFERENCE
>>           ATOMS 1 2 1 3
>>        &END DISTANCE_DIFFERENCE
>>      &END COLVAR
>>    &END SUBSYS
>> &END FORCE_EVAL
>> &GLOBAL
>>    RUN_TYPE MD
>>    PROJECT cp2k
>>    PRINT_LEVEL LOW
>> &END GLOBAL
> >