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Software developed in the team

Published on 18 October 2022
The laboratory has a strong tradition on developing original numerical methods and softwares in solid state physics from ab initio to continuum models. These softwares are developed in collaboration with other laboratories specialists in physics as well as mathematics or computer sciences. They are used in a wide range of applied physcis problems. We also collaborate actively to the development of the code ABINIT in where BigDFT is integrated.

BigDFT is a linear-scaling DFT electronic structure code using a Daubechies wavelet basis set, first developed from an European program. Wavelets form a real space basis set distributed on an adaptive mesh (two levels of resolution in our implementation). BigDFT is massively parallel with an efficiency of 90% and exploits Graphics Processing Units (GPU) architecture. GTH or HGH pseudopotentials are used to remove the core electrons. Thanks to our Poisson solver based on a Green function formalism, periodic systems, surfaces and isolated systems can be simulated with the proper boundary conditions.
The Fiesta code implements the GW and Bethe-Salpeter formalisms using Gaussian basis and resolution-of-the-identity techniques (RI-SVS density and RI-V Coulomb metric). Dynamical screening contribution to the self-energy is explicitely accounted for through a contour deformation approach. Self-consistency on the wavefunctions is implemented at the static COHSEX level. Tamm-Dancoff approximation (TDA) or full Bethe-Salpeter calculations can be performed. The code presently reads input Kohn-Sham eigenstates from the open-source Siesta and NWChem packages so that all-electron or pseudopotential calculations can be performed with standard quantum chemistry bases or with the numerical orbitals generated by the Siesta package (requesting then a Gaussian fit of the radial part of the basis). Any DFT code dumping all Kohn-Sham eigenstates (occupied/unoccupied) expressed on a Gaussian basis, plus the exchange-correlation contribution to the Kohn-Sham eigenvalues, can be branched very straighforwardly onto the Fiesta code.
TB_Sim is a k.p and tight-binding code developed at CEA Grenoble. It is able to compute the structural, electronic, optical and transport properties of various kinds of nanostructures such as semiconductor nanocrystals, nanowires and carbon nanotubes.
Mi_Magnet simulates magnetic system in the model of Heisenberg classical spins using a multi-resolution approach based on a domain decomposition. Using multipole methods, large system of many million sof variables are feasible.
V_Sim visualizes atomic structures such as crystals, grain boundaries and so on. The rendering is done in 3D to represent the atoms. The user can interact through many functions to choose the view, the size of the atoms, their color, the background color, the type of fog...