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Re: [lammps-users] TIP4P long range solver
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Re: [lammps-users] TIP4P long range solver


From: Axel Kohlmeyer <akohlmey@...24...>
Date: Mon, 20 Nov 2017 16:18:28 -0500

you can also model TIP4P without any of the "tip4p" styles, by defining it through 4 explicit sites and using fix rigid or fix rigid/small  instead of fix nve + fix shake to do time integration for the TIP4P water molecules. please search the mailing list archives, this topic has been discussed several times.

axel.

On Mon, Nov 20, 2017 at 4:16 PM, Axel Kohlmeyer <akohlmey@...24...> wrote:


On Mon, Nov 20, 2017 at 4:14 PM, Ali Morshedi <morshedi1370@...24...> wrote:
Dear axel,

Thanks for the response. One more thing:

Does that mean that currently it's not possible to use ewald summation with TIP4P because we don't have "ewald/tip4p" option?

​pppm is equivalent to ewald and usually (much) faster.​

axel.

 

Best,
Ali

On Mon, Nov 20, 2017 at 1:03 PM, Axel Kohlmeyer <akohlmey@...24...> wrote:


On Mon, Nov 20, 2017 at 2:39 PM, Ali Morshedi <morshedi1370@...24...> wrote:
Dear lammps-users,

I use TIP4P model of water in my system. For pair style, I'm setting the following;

pair_style hybrid buck/coul/long 8.5 lj/cut/tip4p/long 3 4 2 4 0.1546 8.5

In the doc page for lj/cut/tip4p/long it is written: "style lj/cut/tip4p/long is for use with a long-range Coulombic solver (Ewald or PPPM)."
Is it correct to infer that if I'm using lj/cut/tip4p/long, then "kspace_style ewald 1e-6" will take into account the charge distance from O site in TIP4P?

​that is not correct.​
 

If so, then why is there a special "pppm/tip4p" to account for long range forces?

​it is there because you must have a modified long-range solver to account to the charge at a different location than the oxygen location without explicitly defining its position.

axel.​

 

I'm using 11Aug17 version of lammps.

Thank you and best regards,

Ali

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--
Dr. Axel Kohlmeyer  akohlmey@...24...  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.




--
Dr. Axel Kohlmeyer  akohlmey@...24...  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.



--
Dr. Axel Kohlmeyer  akohlmey@...92......  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.