CST:Constraints

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Each collective variable employed by the constrained dynamics simulation is provided in a separate [CV] section. These sections are placed either in a special group, {CST} by default, when the collective variables are defined in the main control file, or in the {MAIN} group of a separate file. The name of the group or the file is controlled by the fcstdef option in the [files] section.

[CV]

Key	Default value	Type	Description
name		string	The name of a collective variable from the list of general collective variables. For details, see Collective variables.
value		real	The value at which the constraint should be fixed. If this key is not provided, or it is a character '@', the value of the collective variable measured at the PMFLib startup is used. If the constrained dynamics simulation is restarted, the value from the restart file is used instead.
change_to		real	The constraint value is changed continuously from its initial value to the value provided by this key. This option is mutually exclusive with change_to_bin, increment, increment_by_bins, and control_file.
increment		real	The constraint value is changed continuously from its initial value by the increment provided by this key. This option is mutually exclusive with change_to, change_to_bin, increment_by_bins, and control_file.
control_file		string	The name of a file containing externally controlled constraint values. The file must contain at least fnstlim values, one value for each MD step. If this key is provided, the constraint value is controlled by the file and the keys change_to, change_to_bin, increment, and increment_by_bins are ignored.
[cst]/freadranges on
min_value		real	The minimum value of the CV range. This key is read only if freadranges is enabled in the [cst] section. In that case, this key is mandatory.
max_value		real	The maximum value of the CV range. This key is read only if freadranges is enabled in the [cst] section. In that case, this key is mandatory. The value must be greater than min_value.
nbins		integer	The number of bins used to discretize the CV range. This key is read only if freadranges is enabled in the [cst] section. In that case, this key is mandatory and its value must be greater than zero.
value_at_bin		integer	The bin index at which the constraint should be fixed. The constrained value is set to the centre of the selected bin. This key requires CV ranges to be read by enabling freadranges in the [cst] section. The bin index must be within the range from 1 to nbins. This option is mutually exclusive with value.
change_to_bin		integer	The constraint value is changed continuously from its initial value to the centre of the bin specified by this key. This key requires CV ranges to be read by enabling freadranges in the [cst] section. This option is mutually exclusive with change_to, increment, increment_by_bins, and control_file.
increment_by_bins		integer	The constraint value is changed continuously from its initial value by an increment corresponding to the specified number of bins. This key requires CV ranges to be read by enabling freadranges in the [cst] section. This option is mutually exclusive with change_to, change_to_bin, increment, and control_file.

Keys in bold are mandatory.

NOTE: If the CV is a member of a managed path controlled by the path subsystem, then its constrained value is managed by the path and the local value, value_at_bin, change_to, change_to_bin, increment, increment_by_bins, and control_file keywords should not be specified.