We have developed a pairwise additive potential model to describe the macroscopic elastic interactions of a chiral nematic liquid crystal. The potential is obtained from the expression for the elastic free energy density discretized onto a cubic lattice and mapped onto a suitable expansion in scalar invariants. ne value of the pair potential is explored by means of a Monte Carlo lattice computer simulation. It allows, in a simple and efficient way, the simulation of liquid crystal devices and samples in confined geometries, taking into account the effect of the temperature of the sample and of the thermal fluctuations in the director distribution, as well as the elastic interactions.