The Spex code

Spex is an independent program and part of the Jülich FLAPW code family.

It gives access to theoretical spectra and quasiparticle properties employing BSE and the GW approximation. As it is based on the all-electron FLAPW method, a large variety of materials can be treated. The code was written with a focus on computational efficiency and ease of use.


  • GW, HF, COHSEX, and PBE0 calculations for semiconductors, insulators, and metals
  • RPA total-energy calculations
  • EELS spectra (RPA)
  • Optical spectra (BSE)
  • Magnetic response (BSE)
  • Spin-orbit coupling
  • Treatment of spin-polarized systems and (semi)core states
  • Self-energy evaluated with analytic continuation or contour integration
  • Self-consistent GW (HF, COHSEX, PBE0) calculations
  • Self-energy with magnon vertex GWT
  • Wannier support (e.g., Wannier interpolation)
  • Hubbard U parameters (cRPA)
  • Parallelisation

Missing Features * Non-collinear magnetism (SOC can be included in second variation, though) * TDDFT (discontinued)

Spex is written and maintained by Christoph Friedrich. Contributions by Irene Aguilera, Ersoy Sasioglu, Mathias Müller, Markus Betzinger, Stefan Rost, Anoop Chandran, Dmitrii Nabok.

Financial support from the Deutsche Forschungsgemeinschaft through the Priority Programm 1145 "Modern and universal first-principles methods for many-electron systems in chemistry and physics" is gratefully acknowledged.

For further questions about Spex, write to Spex users.

Click here to register and download Spex. Click here for the Spex Manual.