[ESPResSo-users] Trying to understand force_calc

[Evyatar Arad]

Hello again everyone,

While going through the code of Velocity-Verlet integrator, I’ve noticed the 
3rd integration step is preformed with a call to “force_calc”.
One of the comments describing the function stated that the forces are 
initialised with “friction_thermo_langevin” from the thermostat.cpp code ( 
"Initialise forces with: \ref friction_thermo_langevin (ghost forces with 
zero)”).
This may come as trivial, why are the langevin coefficients needed to 
initialise the particle forces?
Also, I couldn’t actually find any reference in the “force_calc” function’s 
body to “friction_thermo_langevin” or  “init_local_particle_force”. When and 
where does “friction_thermo_langevin” actually gets called?

Have a great week, thanks in advance,
Evyatar.