Action: ECV_CUSTOM

Module	opes
Description	Usage
Use some given CVs as a set of expansion collective variables (ECVs).

Details and examples

Use some given CVs as a set of expansion collective variables (ECVs).

This can be useful e.g. for quickly testing new ECVs, but from a performance point of view it is probably better to implement a new ECV class.

By default the ARGs are expeted to be energies, $\Delta U_i$ , and are then multiplied by the inverse temperature $\beta$

$\Delta u_i=\beta \Delta U_i\, .$

Use the DIMENSIONLESS flag to avoid this multiplication.

The flag ADD_P0 adds also the unbiased distribution to the target. It is possible to specify a BARRIER as in ECV_UMBRELLAS_LINE, to avoid a too high initial bias.

Examples

Click on the labels of the actions for more information on what each action computes

eneThe ENERGY action with label ene calculates the following quantities: Quantity    Type    Description  
ene scalar the internal energy: ENERGYCalculate the total potential energy of the simulation box. More details
t1The CUSTOM action with label t1 calculates the following quantities: Quantity    Type    Description  
t1 scalar an arbitrary function: CUSTOMCalculate a combination of variables using a custom expression. More details PERIODICif the output of your function is periodic then you should specify the periodicity of the function=NO ARGthe values input to this function=ene FUNCthe function you wish to evaluate=(300/500-1)*x
t2The CUSTOM action with label t2 calculates the following quantities: Quantity    Type    Description  
t2 scalar an arbitrary function: CUSTOMCalculate a combination of variables using a custom expression. More details PERIODICif the output of your function is periodic then you should specify the periodicity of the function=NO ARGthe values input to this function=ene FUNCthe function you wish to evaluate=(300/1000-1)*x
ecvThe ECV_CUSTOM action with label ecv calculates the following quantities: Quantity    Type    Description  
ecv.t1 scalar the value of the argument named t1
ecv.t2 scalar the value of the argument named t2: ECV_CUSTOMUse some given CVs as a set of expansion collective variables (ECVs). More details ARGthe labels of the single ECVs=t1,t2 TEMP temperature=300 ADD_P0 add the unbiased Boltzmann distribution to the target distribution, to make sure to sample it
opesThe OPES_EXPANDED action with label opes calculates the following quantities: Quantity    Type    Description  
opes.bias scalar the instantaneous value of the bias potential: OPES_EXPANDEDOn-the-fly probability enhanced sampling with expanded ensembles for the target distribution. This action has hidden defaults. More details ARGthe label of the ECVs that define the expansion=ecv.* PACEhow often the bias is updated=500
opes: OPES_EXPANDEDOn-the-fly probability enhanced sampling with expanded ensembles for the target distribution. This action uses the defaults shown here. More details ARGthe label of the ECVs that define the expansion=ecv.* PACEhow often the bias is updated=500  OBSERVATION_STEPS number of unbiased initial PACE steps to collect statistics for initialization=100 FILE a file with the estimate of the relative Delta F for each component of the target and of the global c(t)=DELTAFS PRINT_STRIDE stride for printing to DELTAFS file, in units of PACE=100

It is equivalent to the following:

Click on the labels of the actions for more information on what each action computes

eneThe ENERGY action with label ene calculates the following quantities: Quantity    Type    Description  
ene scalar the internal energy: ENERGYCalculate the total potential energy of the simulation box. More details
ecvThe ECV_MULTITHERMAL action with label ecv calculates the following quantities: Quantity    Type    Description  
ecv.ene scalar the value of the argument named ene: ECV_MULTITHERMALExpand a simulation to sample multiple temperatures simultaneously. More details ARGthe label of the internal energy of the system=ene TEMP temperature=300 TEMP_SET_ALLmanually set all the temperatures=300,500,1000
opesThe OPES_EXPANDED action with label opes calculates the following quantities: Quantity    Type    Description  
opes.bias scalar the instantaneous value of the bias potential: OPES_EXPANDEDOn-the-fly probability enhanced sampling with expanded ensembles for the target distribution. This action has hidden defaults. More details ARGthe label of the ECVs that define the expansion=ecv.* PACEhow often the bias is updated=500
opes: OPES_EXPANDEDOn-the-fly probability enhanced sampling with expanded ensembles for the target distribution. This action uses the defaults shown here. More details ARGthe label of the ECVs that define the expansion=ecv.* PACEhow often the bias is updated=500  OBSERVATION_STEPS number of unbiased initial PACE steps to collect statistics for initialization=100 FILE a file with the estimate of the relative Delta F for each component of the target and of the global c(t)=DELTAFS PRINT_STRIDE stride for printing to DELTAFS file, in units of PACE=100

Input

The arguments that serve as the input for this action are specified using one or more of the keywords in the following table.

Keyword	Type	Description
ARG	scalar	the labels of the single ECVs

Full list of keywords

The following table describes the keywords and options that can be used with this action

Keyword	Type	Default	Description
ARG	input	none	the labels of the single ECVs
TEMP	compulsory	-1	temperature
NUMERICAL_DERIVATIVESThis keyword do not have examples	optional	false	calculate the derivatives for these quantities numerically
ADD_P0	optional	false	add the unbiased Boltzmann distribution to the target distribution, to make sure to sample it
DIMENSIONLESSThis keyword do not have examples	optional	false	consider ARG as dimensionless rather than an energy, thus do not multiply it by beta
BARRIERThis keyword do not have examples	optional	not used	a guess of the free energy barrier to be overcome (better to stay higher than lower)

Quantity	Type	Description
ene	scalar	the internal energy