Programs in Physics & Physical Chemistry
|[Licence| Download | New Version Template] aedf_v1_0.tar.gz(4780 Kbytes)|
|Manuscript Title: SaX: An open source package for electronic-structure and optical-properties calculations in the GW approximation|
|Authors: Layla Martin-Samos, Giovanni Bussi|
|Program title: SaX (Self-energies and eXcitations)|
|Catalogue identifier: AEDF_v1_0|
Distribution format: tar.gz
|Journal reference: Comput. Phys. Commun. 180(2009)1416|
|Programming language: FORTRAN, plus some C utilities.|
|Computer: Linux PC, Linux clusters, IBM-SP5.|
|Operating system: Linux, Aix.|
|Has the code been vectorised or parallelized?: Yes|
|RAM: depending on the system complexity|
|Keywords: electronic properties, optical properties, GW self-energy, Bethe-Salpeter, plane-waves, object-oriented programming.|
|PACS: 71.15.-m, 71.15.Qe, 71.35.-y.|
External routines: Message-Passing Interface (MPI) to perform parallel computations. ESPRESSO (http://www.quantum-espresso.org)
Nature of problem:
SaX is designed to calculate the electronic band-structure of semiconductors, including quasi-particle effects and optical properties including excitonic effects.
The electronic band-structure is calculated using the GW approximation for the self-energy operator. The optical properties are calculated solving the Bethe- Salpeter equation in the GW approximation. The wavefunctions are expanded on a plane-waves basis set, using norm-conserving pseudopotentials.
Many objects are non-local matrix represented in plane wave basis sets. The memory required by the program in the allocation of such objects increases with the increase of the simulation cell volume. Other quantities are built calculating electronic transitions, so that the computational time increase with their number, and scales as Nv × Nc × Nk2, where Nv and Nc are the number of valence and conduction bands implied in the transition and Nk is the number of special k vectors. Symmetries are not exploited yet. Finally, metallic systems cannot be studied yet.
SaX is written using FORTRAN90 in an object-oriented way. Thus, it is easy to add new features and to reuse the code.
The 3 examples, contained in the distriburion file, each take only a few seconds to run. For systems of interest, the run may take a number of days with a typical memory allocation of 1600Mb per processor.
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