[Pw_forum] Constraint on centre of mass of a molecule

[Ngoc Linh Nguyen]

siva rama krishna wrote:
> 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 ?
Yes, you can. By put "if_pos(nat)(3) = 0" for all atoms in the molecule  
the Z-component of the center of mass of the molecule will be unchanged

Linh

>
> Thanks and Regards,
>
> Sivaramakrishna J
> Member of Technical Staff
> Computational Research Labs, Pune.
> India
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