Extract particle properties only once for each new contact

Hello everyone,

I am trying to extract particle velocity and position only one time for each collision, by reading the output only in the first timestep the contact takes place and ignore the output for the rest of contact duration. I want to use these properties by variable command and fix adapt to update particle diameter.

I tried to use "pair/gran/local command", but this command gives me the output every timestep the two particles are in contact and that's not what I needed. I want only one particle property reading for the whole duration of each contact.

Is there any way or command that can give me the output this way ?

Any help would very appreciate.

Thanks in advance,

Senan