Hi Carlos and Dave,
That is a good point. It seems it doesn’t matter when using SHAKE since it is rigid.
I am just curious if SHAKE was not used, is 50.0 kcal/(mol*Rad^2) a better choice
than 100.0 kcal/(mol*Rad^2)?
Best regards,
Pengfei
> On Apr 5, 2018, at 8:20 AM, David Cerutti <dscerutti.gmail.com> wrote:
>
> 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
