harmonic restraint functional form

Ali RNAlo... at gmail.com
Tue May 6 04:57:13 UTC 2008


Dear cp2k users,

I just wanted to check this to confirm. As far as I can tell the
functional form for the harmonic restraint within the MOTION%CONSTRAINT
%COLLECTIVE%RESTRAINT is:

k(x-x_o)^2

and NOT (k/2)(x-x_o)^2.

I am used to seeing the latter in most of functional forms for the
harmonic potential but I guess the implementation is the former. This
isn't a complaint but more so a check to make sure that this is true.
In fact in all the sections (except the FORCEFIELD section where you
can select the functional form depending on whether you use CHARMM or
GROMOS), for example when one uses the ddap_constraints, the
functional form for the harmonic potential is the latter of the above.

Ali


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