YAMBO code


Yambo is a computer software package for studying many-body theory aspects of solids and molecule 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. It is an open-source software released under the GNU General Public License. However the main development repository is provate and only a subset of the features available in the private repository are cloned into the public repository and thus distributed.

Excited state properties

Yambo can calculate:
Yambo can treat molecules and periodic systems in three dimensions
two dimensions and one dimension. It can also handle collinear and non-collinear magnetic systems.
Typical systems are of the size of 10-100 atoms, or 10-400 electrons, per unit cell in the case of periodic systems.

Theoretical methods and approximations

Yambo relies on many-body perturbation theory and time-dependent density functional theory. Quasiparticle energies are calculated within the GW approximation for the self energy. Optical properties are calculated either by solving the Bethe–Salpeter equation or by using the adiabatic local density approximation within time-dependent density functional theory.

Numerical details

Yambo uses a plane waves basis set to represent the electronic 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.

Technical details

Part of the YAMBO code is kept under a private repository.
These are the features implemented and not yet distributed: