YAMBO Code

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Yambo is an open source Many-body theory software package for study solids and molecular systems. It calculates the excited state properties of physical systems from first principles (e.g. from quantum mechanics law without the use of empirical data). Yambo can treat molecules and periodic systems (both metallic an insulating) in three dimensions (crystalline solids) two dimensions (surfaces) and one dimension (e.g. nanotubes, nanowires, polymeric chains). Typical systems are of the size of 10-50 atoms/10-200 electrons (per unit cell in the case of periodic systems). Yambo uses a plane-wave basis set to represent the electronic (single-particle) wavefunctions. Core electrons are described with norm-conserving pseudopotentials. The choice of a plane-wave basis set enforces the periodicity of the systems. Isolated systems, and systems that are periodic in only one or two directions can be treated by using a supercell approach. For such systems Yambo offers two numerical techniques for the treatment of the Coulomb integrals: the cut-off and the random-integration method.