Self-assembly of adenine-dimer chains on Cu(1Â 1Â 0): Driving forces from first-principles calculations

The formation of self-assembled adenine-dimer chains on the Cu(1 1 0) surface is studied theoretically by means of ab initio calculations. The main driving forces for the appearance of the long-range order within the molecular overlayer are identified. The stable and metastable adenine overlayers are the result of the interplay between dimer bonding, intra- and interchain interactions and geometry effects imprinted by the metal surface. An adsorption pathway is proposed to explain the characteristic directionality of the dimer chains. Scanning tunneling microscopy images are computed for the optimized chain structures and compared with the available experimental data.