[Pw_forum] Constraint on centre of mass of a molecule

[siva rama krishna]

Dear Users,

Could anyone please let me know how to write a new constraint on the centre
of mass of a molecule.
I want to allow an approaching molecule onto a substrate to move along XY
plane while its Z-component of centre of mass is arrested.
One can arrest the Z-component of an atom by setting ' if_pos(nat)(3)=0 '
for the atom with index number 'nat'.
Similarly, can we arrest the Z-component of the centre of mass of a molecule
?

Thanks and Regards,

Sivaramakrishna J
Member of Technical Staff
Computational Research Labs, Pune.
India
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