We present Monte Carlo simulations in the NVT ensemble for spherical particles of diameter or interacting via a hard-core potential with a square-shoulder (SS) repulsive barrier, a square-well (SW) attraction, and a second SS repulsion. This discrete potential is used to mimic the pair interaction in confined colloidal systems at the air/water interface. The SW attraction represents a secondary minimum for-large interparticle distances, and the SS repulsion is a shallow secondary maximum after the secondary minimum. The effect of the SS range lambda(r)sigma is studied for the cases lambda(r) = 0, 6, and 7. The simulation results for the last two cases indicate the important role of the presence of the secondary maximum in-the inter-action potential, since they are able to reproduce the main features observed in colloidal particles trapped at the air/water interface, such as clustering, chain formation, foams, and the presence of voids. [References: 30]
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