maxwell stress tensor in RF module

Hello all

I want to use maxwell stress tensor it in RF module to calculate the force on a dielectric particle above a surface, The particle is illuminated with a planewave. I already did the calcuation by manually define MST and then integrate it on upper and lower surface surroundingteh particle but as far as I understood COMSOL has a built in expresions for different components of MST tensor. As my particle is in water I need to correct the exprassions ( I don't know where can I read more and learn more about what each exprassion is and means and alos how are they calculated) .

has anybody worked with MST in Rf module?

Thanks