Recording Particle-Particle Collisions

Hello Everyone,

I have a query regarding the simulation I am doing right now regarding slurry flow (carbon particles moving in a flowing water) in a microchannel to simulate charge transfer between particle-collector and particle-particle.

I have implemented
(1) DEM Collisions between particle-particle and particle-wall using LIGGGHTS.
(2) Brownian Motion in particles using self-made LIGGGHTS script.
(3) Fluid drag force acting on particles using self-made LIGGGHTS script.
(4) Gravitational drag force acting on particles using self-made LIGGGHTS script.

My question is there a way to record the particles that are being in contact with each other and modify some scalar data based on that?
Means compute contact/atom generates atom-type data in zeros (if that particle is not in contact with other) and ones (if it is in contact) but it does not recognize which two particles are in contact with each other.
I want to identify which two (or more) particles are colliding with each other at the timestep and records their respective IDs so that i can use that data later on.

Another question is that is there a way to use conditional statements for atom-type data since IF THEN statement does work only for global variables and not atom-type variables.

Please reply
Thank you