[lammps-users] Support of the pair_modify command

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1

Dear

We have defined some potentials that have different special bonds depending on their type. We end up with the definition

special_bonds lj 0.5 0.5 0.5 coul 0.5 0.5 0.5

pair_modify pair lj/cut special lj 0.0 0.0 0.0

pair_modify pair lj/cut/coul/cut special lj 0.0 0.0 1.0 special coul 0.0 0.0 1.0

This works well for us with Lammps 2021 version. In another cluster though where we use the 2019 version we get the error below:

ERROR: Illegal pair_modify command (src/pair.cpp:187)

Last command: pair_modify pair lj/cut/coul/cut special lj 0.0 0.0 1.0 special coul 0.0 0.0 1.0

The question is, whether this style of pair_modify command is only supported in Lammps 2021 or if it should have worked for us. The latter would mean there is some other error we have not spotted.

Best Regards

2

I believe that syntax for pair_modify is new in the last couple years. Your 2019 installation
should have a doc/src dir with the pair_modify.rst file that documents that command for
that version. Reading it will give you a definitive answer.

Steve

3

You can also download old tarballs from 2019 from the LAMMPS download site. They
will have that pair_modify.rst file.

Steve