On the Nature of Tellurium Atomic Helices

A theoreticsal study of single, double and triple hydrogen-terminated chains of tellurium atoms is presented. Surprisingly, H-terminated single chains with 3 Te atoms per unit cell (as in Te crystals) are found to be unstable. They relax to helices with lower energies and smaller twist angles. However, some compact disordered Te chains of mixed chirality are found to have still lower energies. Pairs of H-terminated Te atomic chains are found to form DNA-like double helices with lower energies than compact disordered structures of the two chains. Triplets of H-terminated Te atomic chains are found to form triple helices. The single, double and triple Te helices reported here are beyond the scope of previously studied periodic models with small unit cells.