Dear users,
I need to simulate a large system of epoxy polymer using Lammps and Dreiding force field. I’ve built my model in Accelrys Materials Studio, however don’t know how to convert it to initial lammps data file. I’m familiar with msi2lmp, however I didn’t find dreiding.frc file for msi2lmp for my current job. I wonder if there is dreiding.frc file out there. please help me with this issue.
Thanks
Behrouz
If dreiding.frc is a force field file, then LAMMPS doesn’t provide
Accelrys ff files. They are proprietary to Accelrys. The only
reason for a user to use msi2lmp is if they have Accelyrs,
so we assume you have the ff files you want to use.
Steve
Dear Steve,
Thank you for your reply. you are right, however, the provided dreiding ff is not formatted as .frc file but it is available as dreiding.off which I think can not be used by msi2lmp. I wonder if there is any way to convert available .off file the suitable .frc file. I’m not a skilled programmer, but think it can be done through programming.
Best
Dear Steve,
Thank you for your reply. you are right, however, the provided dreiding ff
is not formatted as .frc file but it is available as dreiding.off which I
think can not be used by msi2lmp.
Searching google for "dreiding.off", this dreiding.off file appears to
be distributed by Acrylis as well. I did not find a freely available
public version of this particular file. But there is a "dreiding.lib"
file available on the GULP web site.
http://projects.ivec.org/gulp/libraries/dreiding.lib
(I suppose one can always read the original 1990 paper which publishes
the basic set of Dreiding parameters.)
I am I wonder if there is any way to convert
available .off file the suitable .frc file.
not yet.
(at least not for free. I'm assuming Acrylis software is not free.)
I'm not a skilled programmer,
but think it can be done through programming.
Yes.
I suspect many LAMMPS users are comfortable with being required to do
a little programming. I'm hoping to make it easier.
There is a "moltemplate" molecule building program for LAMMPS. I have
been shamelessly promoting this program on the LAMMPS mailing list
last year.
That program can create LAMMPS data files and input scripts, create
bonded angle interactions, and automatically assign force-field
parameters according to atom type. (The upcomming version supports
AMBER's GAFF force field.) It should be possible to create an .LT
file which contains the DREIDING force-field parameters, but I can not
promise that I will have time to do this. Perhaps someone else is
willing to convert the "dreiding.lib" file into .LT format? (and test
to make sure it is working?)
I can definitely help too.
(Moltemplate can assign two-body bond parameters by atom type, but
this feature is not yet documented. This feature would be needed to
convert the dreiding force field into LT (moltemplate) format. I will
update the documentation soon, but am also happy to explain how this
works by email, if anyone wants to try converting force-fields into LT
format. I just don't have the time or knowledge to test the results.)
Cheers
Andrew