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Re: [lammps-users] Assigning BornMayer potential+ ZBL potential
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Re: [lammps-users] Assigning BornMayer potential+ ZBL potential


From: Meral Sharkas <eng_meral.sh10@...16...>
Date: Mon, 17 Jul 2017 10:07:20 +0000 (UTC)

Thank you Axel for your help,

So after looking further in the literature I found that the function governing the system can be described as :

V(r)=F(r) VBm(r) + (1- F(r)) VZbl(r)

VBm : Bornmayer Potential
VZbl: Ziegler Biersack potential


So I just want to confirm that I understood correctly how to create the tabulated potential please. Should i generate a code to evaluate the potential energy for each pair of atoms (ex: Zr-O, Zr-Zr)...etc for different "r" by substituting in the mentioned above relation and then use pair_style table to assign the potential to lammps and then use pair write to check on the evaluated potential?

Also will each pair of atoms have a separated potential file or the whole potential of the system will be in the same file?

I apologize if it is a vague question, I am just trying to get through this field from scratch

Thanks in advance


On Saturday, June 24, 2017 7:05 PM, Axel Kohlmeyer <akohlmey@...24...> wrote:




On Fri, Jun 23, 2017 at 2:54 PM, Meral Sharkas via lammps-users <lammps-users@...430...orge.net> wrote:
Dear Lammps users,

I am new in the molecular dynamics field, I am trying to simulate radiation damage in Zircon (ZrSiO4). I am facing issues in assigning the potential in LAMMPS. According to the literature, the potential is a Born Mayer potential, coulombic part and the Born mayer potential is joined smoothly to a repulsive ziegler Biersack Littmark (ZBL) for very short range interactions.

My questions please are:

1-Is this type of potential expressed by "Hybrid overlay style" in LAMMPS? if Not; how can I join the ZBL to Born Mayer potential?

​pair style hybrid/overlay will just add potentials.​
so ​you either have to program a custom ​pair style or generate (and test) tables for pair style table and overlay then with a suitable coulomb style.

 
2- As per the literature, potential parameters are for Si-O , Zr-O and O-O, and when I add the coefficients for these pairs, I have an error "All pair coeff are not set", so is there a missing information i should I add to lammps?

​yes. you have no Si-Zr parameters​. if they are not supposed to interact (or come near each other), you can just choose parameters resulting in zero potential energy.


​axel.​

 

I hope you can guide me..

Thank you in advance..

Regards


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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.