atom style/equal style

Hi all,
I want to add a force to each atom according to their atom properties such as their spatial coordinates and velocities, in the case that the force applied to each atom is a function of its coordinate and velocity.
I don’t know how to use them in defining an add force command.
I used variable but It gives me the atom style/equal style Error.
Regards,
Sam

Hi all,
I want to add a force to each atom according to their atom properties such as their spatial coordinates and velocities, in the case that the force applied to each atom is a function of its coordinate and velocity.
I don't know how to use them in defining an add force command.
I used variable but It gives me the atom style/equal style Error.

you have to provide more specific information to get a meaningful answer.

axel.