how to charge particles in ligggths ?

hi i need to charge particles the set command charges atom or molecules i need granules charged to insert them in an electric field to change the particles directions if anyone could help me it would be great i could not find a solution i wanna perform the same thing as in the electrostatic example in the site https://www.cfdem.com/electrostatics thanks in advance hope someone helps me i am stuck for weeks on this thank you in advance