maybe try lammps_create_atoms

Somehow I overlooked this function, but it looks pretty nice:

Create n atoms in one API call!
Takes data vectors that are conveniently in exactly the format rsp2 uses
no stringification in rust, no string parsing in lammps!
shrinkexceed = 1 seems to be designed to solve one of the problems originally faced by sp2. (ironically, rsp2 does not currently bother with designating non-periodic directions despite being largely used for 2D structures; but perhaps it may in the future)

ExpHP / rsp2