Setting individual restraints for various atoms

Florian Gisdon florian... at googlemail.com
Mon Apr 11 13:01:32 CEST 2016


Hi again, I have an update to my post. So far I figured out, that 
restraining atoms is quite easy:
The set up equals that for fixed atoms, just in addition a restraint 
constant has to be defined.

&MOTION
  &CONSTRAINT
     &FIXED_ATOMS
        COMPONENTS_TO_FIX XYZ
        LIST 1 ...
        &RESTRAINT
           K 0.001
        &END RESTRAINT
     &END FIXED_ATOMS
  &END CONSTRAINT
&END MOTION

But looking at my trajectory I realized a strange movement of the 
restrained region compared to the flexible and the totally fixed one. I 
think that the restrained region is really restrained to the initial 
position of those atoms, while the fixed and flexible part is 
translating/rotating in space, which I think could be caused by the QM 
region, which is fit into the QM cell, thus moving the rest (not the 
restraint reference positions!) with it.

Is this behaviour correct or is it a bug?

Florian
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