I'm in agreement with Carlos--the force constants for rigid water models
are placeholders. For SPC-Fw, the angle constant does matter, but
understand it's essentially making a fixed charge water model polarizable,
in a sense.
On Wed, Apr 4, 2018 at 8:17 PM, Carlos Simmerling <
carlos.simmerling.gmail.com> wrote:
> Since the water is rigid and there is a bond between the H atoms, does the
> force constant matter?
>
> On Wed, Apr 4, 2018, 8:14 PM pengfei li <ldsoar1990.gmail.com> wrote:
>
> > Hi Everyone,
> >
> > Does anybody know how does the force constant for HW-OW-HW angle come
> > from? I found it is 100.0 kcal/(mol*Rad^2) but 50.0 kcal/(mol*Rad^2) is a
> > more reasonable choice based on Hessian matrix of B3LYP/6-31G* level of
> > calculations. However, I could not find a value in the original
> TIP3P/TIP4P
> > article (Jorgensen, W. L.; Chandrasekhar, J.; Madura, J. D.; Impey, R.
> W.;
> > Klein, M. L. J. Chem. Phys. 1983, 79, 926-935.). So I am just curious
> about
> > what does the original value come from? Thanks!
> >
> > Best regards,
> > Pengfei
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Received on Wed Apr 04 2018 - 17:30:04 PDT
