Theoretical model of diatomic molecules interacting on a two-dimensional lattice

The coverage-dependent binding energy of interacting dimers is investigated using the lattice gas model. Dimers with distinguishable ends are assumed to interact if they occupy only nearest-neighbor lattice sites. The interaction energy between a pair of dimers will be repulsive if identical ends are in nearest-neighbor positions and attractive if they are not. The grand partition function is derived by using the Bethe approximation. The energy of the system of interacting dimers is evaluated as a function of the lattice coverage at different temperatures and pair interaction potentials. Under the same conditions the average number of all types of nearest-neighbors is evaluated.