Abstract
Motivated by recent interest in the formation of DNA-surface complexes we study the effects of surface and counter-ion charges on the electrostatic fields of charged rod-like macromolecules adsorbed on oppositely charged surfaces. We find that the screening of the rod's fields, due to counter-ions and mobile surface charges, can be either exponential (leading to a finite-range interaction) in the case of weak charging or just algebraic in the case of strong surface charging. We test our analytical results with Monte Carlo simulations.