Variable/atom does not update compute

[akohlmey]

Please read and follow the forum guidelines posted here: Please Read This First: Guidelines and Suggestions for posting LAMMPS questions

Those state that you should always provide information about which LAMMPS version you are using and what platform you are running on, and how you configure/compiled it in case you compiled it yourself.

@rickbatra0z

compute  neighs     all coord/atom cutoff 1.5
variable is_monomer  atom c_neighs==0
variable not_monomer atom c_neighs!=0
group    monomers  variable is_monomer
group    clustered variable not_monomer

When I add this to the peptide example, I get the following error:

ERROR: Variable is_monomer: Variable formula compute cannot be invoked before initialization by a run (src/variable.cpp:1737)
Last command: group    monomers  variable is_monomer

Even if placed after the run, so you are not providing sufficient information here or else you should get the same error. Or you are using an older version of LAMMPS that does not print an error but should.