Fixing atoms and distances in Geometry optimization calculations

[miqueleg]

I was planning to try QUICK to find some Transition States, but I cannot find a proper way to fix some atoms and distances in a geometry optimization calculation (in Gaussian is done using the "modredundant" keyword).

My idea was to use the amber implementation to add some restraints to the system, but it seems like a bad idea.
Is there a better way to do this in QUICK?

Thanks,
Miquel