ECV_CUSTOM
This is part of the opes module
It is only available if you configure PLUMED with ./configure –enable-modules=opes . Furthermore, this feature is still being developed so take care when using it and report any problems on the mailing list.

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
tested on v2.8
ene: ENERGY 
t1: CUSTOM 
PERIODIC
compulsory keyword if the output of your function is periodic then you should specify the periodicity of the function.
=NO
ARG
the input for this action is the scalar output from one or more other actions.
=ene
FUNC
compulsory keyword the function you wish to evaluate
=(300/500-1)*x t2: CUSTOM
PERIODIC
compulsory keyword if the output of your function is periodic then you should specify the periodicity of the function.
=NO
ARG
the input for this action is the scalar output from one or more other actions.
=ene
FUNC
compulsory keyword the function you wish to evaluate
=(300/1000-1)*x ecv: ECV_CUSTOM
ARG
compulsory keyword the labels of the single ECVs, \f$\Delta U_i\f$, in energy units
=t1,t2
TEMP
compulsory keyword ( default=-1 ) temperature.
=300
ADD_P0
could not find this keyword
opes: OPES_EXPANDED
ARG
compulsory keyword the label of the ECVs that define the expansion.
=ecv.*
PACE
compulsory keyword how often the bias is updated
=500

It is equivalent to the following:

Click on the labels of the actions for more information on what each action computes
tested on v2.8
ene: ENERGY 
ecv: ECV_MULTITHERMAL 
ARG
compulsory keyword the label of the internal energy of the system.
=ene
TEMP
compulsory keyword ( default=-1 ) temperature.
=300
TEMP_SET_ALL
manually set all the temperatures
=300,500,1000 opes: OPES_EXPANDED
ARG
compulsory keyword the label of the ECVs that define the expansion.
=ecv.*
PACE
compulsory keyword how often the bias is updated
=500
Glossary of keywords and components
Compulsory keywords
TEMP ( default=-1 ) temperature. If not specified tries to get it from MD engine
ARG the labels of the single ECVs, \(\Delta U_i\), in energy units
Options
NUMERICAL_DERIVATIVES ( default=off ) calculate the derivatives for these quantities numerically
ADD_P0 ( default=off ) add the unbiased Boltzmann distribution to the target distribution, to make sure to sample it
DIMENSIONLESS

( default=off ) consider ARG as dimensionless rather than an energy, thus do not multiply it by \(\beta\)

BARRIER a guess of the free energy barrier to be overcome (better to stay higher than lower)