One-dimensional chains of metal atoms

Using a first-principles, density-functional method we have studied the electronic and structural properties of different isolated, periodic and infinite chains of Bi, Tl and Pb. In contrast to the case for crystalline and atomic systems, these have first recently been available experimentally (e.g. as guests inside a zeolite and deposited on surfaces). We have optimized the geometrical parameters as well as calculated the band structures for different structures. We find that the systems are very soft such that the geometry might easily be controlled or influenced by weak external perturbations, e.g. those of the zeolite walls or the surfaces. Some of the structures were found to be unstable without these external interactions. The band structures show that the systems can be either metallic, semiconducting or semimetallic depending on their geometry and structure. It was also found that the inclusion of spin-orbit couplings was essential for a proper description of all the properties. (C) 1997 Elsevier Science Ltd.