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A standalone C++ implementation (a class called
NEP3
) of the neuroevolution potential (NEP) as introduced in the GPUMD package (https://github.com/brucefan1983/GPUMD). We stress that there is no external dependence. Even though the class name isNEP3
, the implementation works for all versions of NEP. -
An interface of the
NEP3
class to the CPU version of LAMMPS (https://github.com/lammps/lammps). It can be run with MPI.
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The
NEP3
C++ class is defined in the following three files:src/nep.h
src/nep.cpp
src/dftd3para.h
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There is an option to use tables to speed up the calculations for the radial functions in NEP. To enable it, one can change line 20 of
src/nep.h
:
// #define USE_TABLE_FOR_RADIAL_FUNCTIONS
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The following folders contain some testing code and results:
test/
test_dftd3/
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The
NEP3
C++ class is used as an engine powering the following Python packages:
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step 1: Copy the files in
src/
intointerface/lammps/USER-NEP/
such that you have the following files ininterface/lammps/USER-NEP/
:nep.h
nep.cpp
dftd3para.h
pair_NEP.h
pair_NEP.cpp
install.sh
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Step 2: Now you can copy the
USER-NEP/
folder intoYOUR_LAMMPS_PATH/src/
and start to compile LAMMPS in your favorite way. Good luck!
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atom_style
can beatomic
andfull
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units
must bemetal
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Specify the
pair_style
in the same way as other potentials in LAMMPS (the first 2 arguments must be * * so as to span all atom types). For example, if you have a NEP modelNEP_HBCN.txt
, and your data file just have element carbon, you can setpair_style nep pair_coeff * * NEP_HBCN.txt C
Firstly, we should set
pair_stype
tonep
, showed in the first line. Then we need set the NEP potential file and atom types by the commandpair_coeff
. Two asterisks* *
mean every atom type will be set an element type orNULL
.NULL
means this potential doesn't consider the atom type. In this example, we set atom type1
in LAMMPS data file to elementC
in NEP potential file. -
The interface also supports multi-element system and hybrid potentials. Take a NEP model
NEP_PdCuNiP.txt
as an example. In this NEP model file, the first line isnep3 4 Pd Cu Ni P
. Then in your LAMMPS input file, the next setting is allowed:pair_style hybrid/overlay nep nep ij/cut 1.0 pair_coeff * * nep 1 NEP_PdCuNiP.txt Cu Ni NULL pair_coeff * * nep 2 NEP_PdCuNiP.txt NULL NULL Pd pair_ceoff 1*2 3 lj/cut 1.0 1.0
The
pair_style
should be sethybrid/overly
or other hybrid methods in LAMMPS. The hybrid potentials should be set after hybrid method. Then, in commandpair_coeff
we need set potential name again to identify which potential is setting for and the number of the potential if more than one. Here, we set two NEP potentials. The first one just computes the NEP potential between atom type1
Cu
and2
Ni
, and of themselves. The second computes NEP potential of atom type3
Pd
itself. -
If you want to calculate the heat current correctly, use the following command to get the 9-component per-atom virial:
compute 1 all centroid/stress/atom NULL
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If you directly or indirectly use the
NEP3
class here, you are suggested to cite the following paper:- Zheyong Fan, Yanzhou Wang, Penghua Ying, Keke Song, Junjie Wang, Yong Wang, Zezhu Zeng, Ke Xu, Eric Lindgren, J. Magnus Rahm, Alexander J. Gabourie, Jiahui Liu, Haikuan Dong, Jianyang Wu, Yue Chen, Zheng Zhong, Jian Sun, Paul Erhart, Yanjing Su, Tapio Ala-Nissila, GPUMD: A package for constructing accurate machine-learned potentials and performing highly efficient atomistic simulations, The Journal of Chemical Physics 157, 114801 (2022).
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If you use the LAMMPS interface of the
NEP3
class, a proper citation for LAMMPS is also suggested.