Allow PLUMED to use collective variables computed in the MD engine.
This feature requires the MD engine to use special instructions to pass to PLUMED the value of some pre-computed collective variable. Check the documentation of the MD code to find out which collective variables can be computed and passed to PLUMED. These variables can then be accessed by name using the EXTRACV action.
Examples
This example takes the lambda variable pre-computed in GROMACS and apply to it a restraint to keep it close to the value 3.
Click on the labels of the actions for more information on what each action computes
l: EXTRACVNAMEcompulsory keyword
name of the CV as computed by the MD engine =lambda The EXTRACV action with label l calculates a single scalar valueRESTRAINTARGthe arguments on which the bias is acting. =lKAPPAcompulsory keyword ( default=0.0 )
specifies that the restraint is harmonic and what the values of the force constants
on each of the variables are =10 ATcompulsory keyword
the position of the restraint =3 The RESTRAINT action with label
lambda: PUTUNITcompulsory keyword
the unit of the quantity that is being passed to PLUMED through this value. =number SHAPEcompulsory keyword ( default=0 )
the shape of the value that is being passed to PLUMED =0 MUTABLE( default=off ) can plumed change the value of the pointer that is passed from the
MD code PERIODICcompulsory keyword
if the value being passed to plumed is periodic then you should specify the periodicity
of the function. =NO The PUT action with label lambda calculates a single scalar valuel: COMBINEARGthe input to this function. =lambdaPERIODICcompulsory keyword
if the output of your function is periodic then you should specify the periodicity
of the function. =NO The COMBINE action with label l calculates a single scalar value
Glossary of keywords and components
Description of components
Quantity
Description
.#!value
the value of the CV that was passed from the MD code to PLUMED
1.13.2