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UNITS

This command sets the internal units for the code. A new unit can be set by either specifying how to convert from the plumed default unit into that new unit or by using the shortcuts described below. This directive MUST appear at the BEGINNING of the plumed.dat file. The same units must be used througout the plumed.dat file.

Notice that all input/output will then be made using the specified units. That is: all the input parameters, all the output files, etc. The only exceptions are file formats for which there is a specific convention concerning the units. For example, trajectories written in .gro format (with DUMPATOMS) are going to be always in nm.

Options
NATURAL

( default=off ) use natural units

LENGTH the units of lengths. Either specify a conversion factor from the default, nm, or A (for angstroms) or um
ENERGY the units of energy. Either specify a conversion factor from the default, kj/mol, or use j/mol or kcal/mol
TIME

the units of time. Either specify a conversion factor from the default, ps, or use ns or fs

Examples
# this is using nm - kj/mol - fs
UNITS LENGTH=nm TIME=fs
If a number, x, is found, the new unit is equal to x (default units)
# this is using nm - kj/mol - fs
UNITS LENGTH=nm TIME=0.001