Plugin mode installtion #5487

Dear Dosu, Thank you for your prompt response. To test this, I have compiled using a precompiled C library on my desktop, and it installed successfully. However, while executing the lmp command, it shows:

LAMMPS (22 Jul 2025 - Update 4)
OMP_NUM_THREADS environment is not set. Defaulting to 1 thread.
using 1 OpenMP thread(s) per MPI task
Open of file libdeepmd_lmp.so failed: /mnt/Data/DP_PLUGUIN/libdeepmd_c/lib/libdeepmd_cc.so: undefined symbol: _ZN6google8protobuf5Arena8AllocateEm
Reading data file ...
triclinic box = (0 0 0) to (27.54365 27.54365 27.54365) with tilt (0 0 0)
1 by 1 by 1 MPI processor grid
reading atoms ...
918 atoms
read_data CPU = 0.005 seconds
ERROR: Unrecognized pair style 'deepmd' (src/force.cpp:275)
Last input line: pair_style deepmd convert_out.pb

This is the first few lines of LAMMPS input:

plugin load libdeepmd_lmp.so #this is copied in the home directory.
units metal
boundary p p p
atom_style atomic
neigh_modify every 1 delay 0 check no
read_data POSCAR.lmp
pair_style deepmd convert_out.pb
pair_coeff * *
variable t equal 100 #Define the temperature
neighbor 2 bin
neigh_modify delay 0 every 1
timestep 0.001 #Define time step
velocity all create $t 3627941 dist gaussian mom yes
velocity all scale $t
fix 1 all nvt temp $t $t 0.1 #iso 0.0 0.0 1.0
thermo 1000
run 20000

Please advise.
Thanks,
Mayank

Hi @mayankaditya,

The error undefined symbol: _ZN6google8protobuf5Arena8AllocateEm means the protobuf library that the precompiled libdeepmd_cc.so was built against cannot be found at runtime. Because loading the plugin fails, LAMMPS doesn't register the deepmd pair style, which causes the subsequent "Unrecognized pair style" error.

The fix is to ensure the dynamic linker can find all shared libraries bundled with the precompiled libdeepmd_c package. Try setting LD_LIBRARY_PATH to include the library directory before running LAMMPS [1]:

export LD_LIBRARY_PATH=/mnt/Data/DP_PLUGUIN/libdeepmd_c/lib:$LD_LIBRARY_PATH
lmp -in your_input.lammps

If that resolves the plugin loading, you can make it permanent by patching the RUNPATH of liblammps.so with patchelf (version ≥ 0.13) [2]:

patchelf --set-rpath '$ORIGIN:/mnt/Data/DP_PLUGUIN/libdeepmd_c/lib' /path/to/liblammps.so

Alternatively, you can set the LAMMPS_PLUGIN_PATH environment variable instead of using the plugin load command in the input file [1]:

export LAMMPS_PLUGIN_PATH=/mnt/Data/DP_PLUGUIN/libdeepmd_c/lib/deepmd_lmp

You can verify which libraries are missing by running:

ldd /mnt/Data/DP_PLUGUIN/libdeepmd_c/lib/libdeepmd_cc.so | grep "not found"

This will show you exactly which shared libraries the linker cannot locate. All of them should be present within the libdeepmd_c/lib directory if the package is complete.

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