Re:

From: Axel Kohlmeyer (akohlmey_at_gmail.com)
Date: Thu Apr 26 2018 - 10:19:18 CDT

..and, of course, nuclear quantum effects are significantly more
relevant for hydrogen atoms than for deuterium or tritium atoms. ;-)

On Thu, Apr 26, 2018 at 11:04 AM, Axel Kohlmeyer <akohlmey_at_gmail.com> wrote:
> On Thu, Apr 26, 2018 at 10:05 AM, Brian Radak <brian.radak_at_gmail.com> wrote:
>> Arguably off-topic:
>>
>> Is it really well-known that the origin of heavy water effects in this
>> context is purely classical?
>
> as a rule of the thumb: for nuclear quantum effects to matter,
> positions have to be highly correlated, e.g. through confinement
> and/or low temperature.
> otherwise, regular thermal fluctuations and corresponding stochastic
> motions will wash them out and temporarily lower barriers where
> tunneling might be relevant to the point of it not being relevant.
>
> isotope effects, though, i.e. changes in the dynamics resulting from
> doubling or tripling the mass of hydrogen atoms, are quite visible for
> water and may justify a reparameterization of classical force field
> parameters, considering how much those depend on assuming a mean field
> approach for simplifying the interactions.
>
> axel.
>
>> NAMD is not setup to do things like path
>> integral MD, which would be needed for proper modeling nuclear quantum
>> effects. I've seen recent work in this area (Thomas Markland comes to mind),
>> but I recall it being done with a specialized MD engine.
>>
>> On Thu, Apr 26, 2018 at 9:56 AM, Jérôme Hénin <jerome.henin_at_ibpc.fr> wrote:
>>>
>>> Giacomo: I have actually checked the results. The top hit I get is this:
>>> https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2154366/
>>>
>>> where the authors develop a modified version of TIP3P they call TIP3P-HW.
>>>
>>> TL;DR indeed!
>>>
>>> On 26 April 2018 at 15:50, Axel Kohlmeyer <akohlmey_at_gmail.com> wrote:
>>>>
>>>> people have done classical MD simulations of heavy water and isotope
>>>> effects since more than a decade before i did my first steps in
>>>> simulating water, and *that* should already be considered ancient
>>>> history by now.
>>>>
>>>> so this is not exactly a hot new topic anymore and thus not much of a
>>>> surprise, that web search results are not popping up straight on top.
>>>>
>>>> on the other hand, because this is such a well established topic, a
>>>> reasonably detailed search of the published literature - which should
>>>> be at the beginning of *any* new research project - should have turned
>>>> up enough information to answer all the questions that were asked and
>>>> thus eliminated the need to post them here.
>>>>
>>>> axel.
>>>>
>>>> On Thu, Apr 26, 2018 at 9:35 AM, Giacomo Fiorin
>>>> <giacomo.fiorin_at_gmail.com> wrote:
>>>> > Have you actually checked the results of the search? The answer is
>>>> > there,
>>>> > but man, it is so... TL;DR
>>>> >
>>>> > On Thu, Apr 26, 2018 at 8:20 AM, Jérôme Hénin <jerome.henin_at_ibpc.fr>
>>>> > wrote:
>>>> >>
>>>> >> http://lmgtfy.com/?q=tip3p+heavy+water
>>>> >>
>>>> >> You're welcome.
>>>> >>
>>>> >> On 26 April 2018 at 14:02, shyam sharma <shyam14u27_at_gmail.com> wrote:
>>>> >>>
>>>> >>> Dear all,
>>>> >>>
>>>> >>> How can I solvate carbon nanotube by heavy water? Can I do this by
>>>> >>> simply
>>>> >>> changing the mass of hydrogen of normal water? Which water model is
>>>> >>> appropriate for this simulation? Can I use the TIP3P water model for
>>>> >>> heavy
>>>> >>> water?
>>>> >>>
>>>> >>> Any kind of help will be appreciable.
>>>> >>>
>>>> >>> Regards
>>>> >>> Shyam
>>>> >>
>>>> >>
>>>> >
>>>> >
>>>> >
>>>> > --
>>>> > Giacomo Fiorin
>>>> > Associate Professor of Research, Temple University, Philadelphia, PA
>>>> > Contractor, National Institutes of Health, Bethesda, MD
>>>> > http://goo.gl/Q3TBQU
>>>> > https://github.com/giacomofiorin
>>>>
>>>>
>>>>
>>>> --
>>>> Dr. Axel Kohlmeyer akohlmey_at_gmail.com http://goo.gl/1wk0
>>>> College of Science & Technology, Temple University, Philadelphia PA, USA
>>>> International Centre for Theoretical Physics, Trieste. Italy.
>>>
>>>
>>
>
>
>
> --
> Dr. Axel Kohlmeyer akohlmey_at_gmail.com http://goo.gl/1wk0
> College of Science & Technology, Temple University, Philadelphia PA, USA
> International Centre for Theoretical Physics, Trieste. Italy.

-- 
Dr. Axel Kohlmeyer  akohlmey_at_gmail.com  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.

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