Issue with hybrid/overlay for spin-lattice coupling in LAMMPS

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1

Hello LAMMPS Developers and Users @julient,

I am running a spin-lattice coupling simulation in LAMMPS using the pair_style hybrid/overlay command with four different potentials: pair_style hybrid/overlay eam/fs spin/exchange 4.5 spin/neel 4.5 spin/dmi 4.5, and the contents of in.Fe.lmp file are as follows

# LAMMPS Input file for spin-lattice dynamics of bcc iron (Fe)

clear
units metal
dimension 3
boundary p p p
atom_style spin

atom_modify map array

#lattice structre
lattice bcc 2.855
region box1 block -50 50 -50 50 -30 30
region cyl_region cylinder z 0 0 15 -3 3
create_box 1 box1
create_atoms 1 region cyl_region

mass 1 55.845
group Fe type 1

pair_style      hybrid/overlay eam/fs spin/exchange 4.5 spin/dmi 4.5 spin/neel 4.5

pair_coeff      * * eam/fs Fe_mm.eam.fs Fe
pair_coeff      * * spin/exchange exchange 4.5 0.025498 0.281 1.999
pair_coeff      * * spin/dmi dmi 4.5 0.005498 0.0 0.0 1.0
pair_coeff      * * spin/neel neel 4.5 0.005498 0.281 1.999 0.0 0.0 1.0

# neighbor
neighbor        0.1 bin
neigh_modify    every 10 check yes delay 20


## initial condition setting
set             group all spin/atom/random 1235489 2.2
#set group all  spin/atom 1.0 1.0 0.0 0.0   
velocity        all create 1 4928459 rot yes dist gaussian

timestep  0.0001
fix 3 all nve/spin lattice moving

thermo 100
thermo_style custom step temp etotal

run 2000

Issue Description

When I run my simulation with all four potentials included, the execution does not proceed beyond the initial setup stage. The output remains stuck at:

image
image1807Ă—421 19.3 KB

The simulation does not crash or give an explicit error; it just does not proceed beyond this point. LAMMPS Version is LAMMPS (19 Nov 2024 - Development), which is compiled with support for spin-lattice coupling.

What I Have Tried

  1. Reducing system size: The issue persists even with a much smaller system of 63 atoms.
  2. Single-core vs. multi-core: The problem occurs with both “mpirun -np 1” and “mpirun -np 24” , so it does not appear to be MPI-related.
  3. Removing one potential at a time:
  • Any combination of three potentials works fine.
  • The issue only appears when all four potentials (“eam/fs” , “spin/exchange” , “spin/neel” , spin/dmi ) are used together.
    4.Reducing interaction cutoff: Changing the cutoffs for “spin/neel” , “spin/dmi” , and “spin/exchange” did not resolve the issue.
  1. Replacing “spin/dmi” or “spin/neel” with another potential: If I replace one of them with another interaction (e.g., biquadratic exchange), the simulation runs fine, which suggests a conflict between spin/neel and spin/dmi when used together.

Questions for Developers

Is there a known limitation or conflict when using “spin/neel” and “spin/dmi”together with** “eam/fs” and “spin/exchange” under “hybrid/overlay”? My research has to require the use of all four potential at the same time, how should I solve this problem?

Any insights or suggestions would be greatly appreciated!

Thank you in advance!

2

Hi,

Please edit your post using the “preformated text” option. Currently, it is very difficult to read.

Simon

3

@simongravelle Thank you for your suggestion! Since I’m still new to LAMMPS, I wasn’t familiar with that formatting option. I’ve now updated my post with the preformatted text for better readability. If you have any additional suggestions, I would be very grateful.

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