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Re: [lammps-users] pcff force field
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Re: [lammps-users] pcff force field


From: Rajesh <creativeidleminds@...24...>
Date: Sun, 27 Aug 2017 10:40:23 +0530

Thank you Vanessa. I checked it and its working fine with pcff.

On Thu, Aug 24, 2017 at 8:53 AM, Vanessa Oklejas <voklejas@...24...> wrote:
See the README doc. It's pretty self-explanatory the flag is '-class 2'. Also make sure that msi2lmp knows where to find the pcff.frc file. If you're not sure where your version of msi2lmp.exe is looking for frc files (this should be designated when you build this tool), I think you can just place a copy of the frc file where you are running the tool and use this flag '- frc ./pcff.frc' for example. 

I can't speak to Andrew's experiences with pcff and cvff, but I would agree that both of these force fields are complicated and not easy to use. If you are new to this, then his suggestion might be the best way to go for you. 

On Wed, Aug 23, 2017 at 8:10 PM Rajesh <creativeidleminds@...24...> wrote:
Dear Vanessa,

Thank you for your advice. I think my version is old September, 2016. I will try with latest version. What will be the special flag for forcefield 2? Any idea? Thank you.

On Thu, Aug 24, 2017 at 8:28 AM, Vanessa Oklejas <voklejas@...24...> wrote:
Please, always email the lammps user list when responding. 

What version of lammps are you using? I believe the most current stable version for download (17 August 2017) lists a force field file (*.frc) for pcff in ./tools/msi2lmp/frc_files/. So I imagine that producing a lammps-style data files using types from the pcff force field should be possible. There are a few places where you might run into stumbling blocks that I can think of off the top of my head: (1) I think pcff is a class 2 type force field, which I think requires a special flag when you invoke msi2lmp. (2) It's possible MS might have additional atom types in their version of pcff that are not present in the pcff.frc file that is part of the lammps distribution. 

---------- Forwarded message ---------
From: Rajesh <creativeidleminds@...24...>
Date: Wed, Aug 23, 2017 at 7:37 PM
Subject: Re: [lammps-users] pcff force field
To: Vanessa Oklejas <voklejas@...24...>


Dear Vanessa,
I tried with msi2lmp tool but it is inconsistent with pcff force field. Cant we use vmd or moltemplate for the same?

On Wed, Aug 23, 2017 at 10:55 PM, Rajesh <creativeidleminds@...24...> wrote:
Thank you Vanessa, will give it a try.

On Wed, Aug 23, 2017 at 10:28 PM, Vanessa Oklejas <voklejas@...24...> wrote:
See the msi2lmp tool located in the tools directory of your LAMMPS package. You need to build this tool before you use it, but that's relatively straightforward. See the README file in the msi2lmp directory for specific instructions.

On Wed, Aug 23, 2017 at 9:50 AM Rajesh <creativeidleminds@...24...> wrote:
Dear Dr Shan

Thank you for your reply. Is there any tool that can convert material studio files to lammps input with all coefficients defined automatically.?


Thanks

On Wed, Aug 23, 2017 at 10:12 PM, Ray Shan <rshan@...1795...> wrote:

Like anyother valence force fields, pcff is invoked via a combination of pair, bond, angle, dihedral, and improper styles.  Pcff belongs to the class2 family, so check the doc page with anything that is “class2”.

 

Ray

 

 

From: Rajesh <creativeidleminds@...24...>
Date: Wednesday, August 23, 2017 at 9:37 AM
To: LAMMPS Users Mailing List <lammps-users@...396...sourceforge.net>
Subject: Re: [lammps-users] pcff force field

 

Dear lammps users

 

I am trying to simulate a polymer in lammps with pcff. Is there any option for pcff field in lammps? How can I achieve this? I didn't find anything in manual on pcff. Any help will be appreciated. I found some file pcff.frc in lammps folder. I think pcff in not included a pair_style in lammps?

 

Thanks 

 

Rajesh


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