You can't read atoms from a data file to add them.
You could make one data file containing several sets
of atoms. Or you can add them one at a time via
create_atoms single. Or you could read the data
file first, then add atoms via create_atoms.
Re: replacing fix - not sure what you want to do,
but you can unfix the first one, then it is gone.
Steve
2009/5/20 弓晓晶 <[email protected]...>: