LAMMPS Integration Mechanics

Hi again, and thanks for all the help so far.

I have one additional question after looking over some of the LAMMPS modules and commands.

From what I understand, the run 0 command only calculates energy/virial quantities, and short-
circuits the calculation of forces or actual integration. I’ve been looking through verlet.cpp and
integrate.cpp to try and understand how this happens in the code, but it isn’t completely clear
to me. I was wondering if someone could explain that process in more detail, and possibly suggest
some source files to look through for further information.

Thomas Allen
Makri Group

A “run 0” calls the setup() method in Verlet, which does
calculate energy and forces - it just doesn’t time integrate
the atoms. Forces are necessary for pressure output
in the thermo. When you do a “run N” for N > 0, the
run() method of Verlet is called.