Method and Scope

ElectrA is an efficient all-electron density functional electronic structure code based on the augmented spherical wave (ASW) method using the atomic sphere approximation (ASA). ElectrA can calculate all properties that derive directly from the energy bands and the one-electron wave functions. Because of its state-of-the-art implementation, the ASA approximation and the use of the Anderson/Broyden charge density mixing, ElectrA is very fast and therefore is the code of choice wherever this approximation is justified [1,2].

Features

• Self-consistent all-electron density functional method using the local (spin) density approximation
• Local density approximation (LDA) and generalized gradient approximation [*] (GGA)
• Full coverage of periodic table
• Semirelativistic (ie. includes mass-velocity and Darwin shifts)
• Spin-polarized treatment of magnetic systems
• Best suited for close-packed materials
• Automated empty spheres construction for treating semi-open structures [3]
• Anderson/Broyden charge density mixing [4]
• Total energies, bulk moduli [*]
• Band structure (spin restricted and spin unrestricted)
• Site-, spin- and partial-wave projected densities of states
• Magnetic moments
• Core level spectra [*]
• Charge and spin densities at the nuclei, isomer shifts, hyperfine fields [*]
• Optical spectra (ie. calculation of optical matrix elements and generation of spectra)
• High computational efficiency (for example, the self consistent electronic structure calculation including band structures, densities of states and optical spectra for TiAl takes about 150 seconds on a laptop with a 350 MHz processor and 64 MB of RAM)

[*] in preparation

Example

Electronic structure of CaTiO3. The structure was retrieved with InfoMaticA. The energy bands, density of states, and partial atomic charges were calculated with ElectrA (automatic addition of empty spheres, automatic choice of sphere radii, defaults for k-space integration). The results were viewed interactively within MedeA. The crystal structure (shown on the left) was rendered via ray-tracing (POV-Ray). Total computing time: 120 seconds with a 450 MHz Pentium II under Windows® 98.

References

1. Volker Eyert,
   Basic notions and applications of the augmented spherical wave method,
   Int. J. Quant. Chem. 77, 1007-1031 (2000), Special Issue: Electronic Structure of Materials, edited by M. Defranceschi.
   
2. ASW Homepage
3. Volker Eyert and Karl-Heinz Höck,
   The electronic structure of V₂O₅: Role of octahedral deformations,
   Phys. Rev. B 57, 12727-12737 (1998).
   
4. Volker Eyert,
   A comparative study on methods for convergence acceleration of iterative vector sequences,
   J. Comput. Phys. 124, 271-285 (1996).
   
   
5. Comprehensive list of ASW Publications
6. J. Kübler and V. Eyert,
   Electronic structure calculations,
   in: Electronic and Magnetic Properties of Metals and Ceramics,
   edited by K. H. J. Buschow (VCH Verlagsgesellschaft, Weinheim, 1992), pp. 1-145;
   Volume 3A of Materials Science and Technology - A Comprehensive Treatment,
   edited by R. W. Cahn, P. Haasen, and E. J. Kramer (VCH Verlagsgesellschaft, Weinheim, 1991-1996).
7. Volker Eyert,
   Electronic structure calculations for crystalline materials,
   in: Density Functional Methods: Applications in Chemistry and Materials Science,
   edited by M. Springborg (Wiley, Chichester, 1997), pp. 233-304.
8. Volker Eyert and Ulrich Eckern,
   Bandstruktur - Von der Quantenmechanik zum Materialdesign,
   Physik in unserer Zeit 31, 276-282 (2000).