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Re: [lammps-users] Help with Miyake potential
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Re: [lammps-users] Help with Miyake potential


From: Axel Kohlmeyer <akohlmey@...24...>
Date: Tue, 22 Aug 2017 23:24:51 -0400



On Tue, Aug 22, 2017 at 9:37 PM, sankha mukherjee <sankha.mukherjee2@...24...> wrote:
Dear LAMMPS users,

The aim of my project is to study the behavior of molten slags (ceramics) of varying composition. To study slags one has to take a mixture of ceramics and melt them at very high temperature. Miyake potential which belongs to the family of Buckingham potentials is used for Al, O, Si, Ca, K, Na systems. While in the past I have worked with Stillinger-Weber, Tersoff, ReaxxFF potentials, Miyake potential is difficult for me. I have tried a lot, but when I try using more than one type of atom the simulation box just blows up or loose atoms or nan temperature.

​have you tried to first unoverlap your system by starting with a (flat) soft potential which you raise over time using fix adapt? you can check out the micelle example for how to do this. just translate the parameters in reduced units to your unit set.

also, i suggest you start with fewer atom types and then test groups of parameter for individual compounds, before doing as complex a system as in your input.


I have tried energy minimization, nve/limit (because I generate atoms randomly), npt, nve, nvt. Have played around with the composition, temperature nothing seems to work. I think I am making mistake with the potential parameters. I know it is an advanced problem, and no one in my research group seems to know how to deal with it. It would be kind if any one of you take a look and help me solve this problem. I am attaching my input file with this email and the citation for Miyake potential.

​actually, it doesn't look like an advanced problem, but just using a basic step-by-step ​procedure to avoid having too many uncontrolled degrees of freedom. i would call this common sense... ;-)

​axel.​

 

A. Miyake, "Interatomic potential parameters for molecular dynamics simulation of crystals in the system K2O-Na2O-CaO-MgO-Al2O3-SiO2" Miner. J., 20 (1998), pp. 189-194

Thanks

Sankha Mukherjee


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--
Dr. Axel Kohlmeyer  akohlmey@...12...24...  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.