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Re: [lammps-users] How to set up the box size for mono-layer graphene
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Re: [lammps-users] How to set up the box size for mono-layer graphene


From: Axel Kohlmeyer <akohlmey@...24...>
Date: Sun, 11 Jun 2017 10:29:51 -0400



On Sun, Jun 11, 2017 at 7:52 AM, JWG <w.g.jiang@...127...> wrote:
Dear all,

I am simulating nanoindentation of mono-layer graphene. We modeled the mono-layer graphene in Lammps. 

boundary f f s
units metal
# create geometry
lattice       custom 1.0 a1 2.46 0.0 0.0 a2 0.0 4.26 0.0 a3 0.0 0.0 3.4 &
                         basis 0.0 0.0 0.0 &
                         basis 0.5 0.16666666667 0.0 &  
                         basis 0.5 0.5 0.0 &
                         basis 0.0 0.66666666667 0.0 
region        graphene block 0 364.14 0 364.14 77.52 80.92 units box
create_box 1 graphene
create_atoms 1 region graphene
mass          1 12.01
group         graphene region graphene
pair_style  airebo 2.5 0 0
#pair_style  rebo
pair_coeff * * ../CH.airebo  C  
timestep 0.001 
minimize 2.3e-16 1.0e-3 200000 200000
---
---
---

but we got an error message: Cannot use neighbor bins - box size << cutoff (../neighbor.cpp:1803).
If I change the region command:
region        graphene block 0 364.14 0 364.14 67.52 80.92 units box,
that is ok. But we cannot get a single-layer graphene.
What mistakes in our input codes? How to correct the codes for get a single-layer graphene?

​the problem is the choice of boundary condition as f f s
this will have the box collapse in z direction, since there are no atoms.
if you use f f m boundary and the box will expand in z, but never shrink below the initial dimensions.

axel.

 
thanks very much.

mike




--
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.