Disabling LJ interactions for some atoms

Supposed I have two types of atoms. Is it possible in Lammps to only calculate LJ interactions for type 1, but not for type 2?

One possible solution I know is to set
pair_coeff 2 2 0. 0.

but LAMMPS would still waste time calculating zeroes, right?



That would work, you could also look at using pair_hybrid
which allows you to specify "none" for some interactions.
That has its own overheads however.