# Requirements

• Libraries
• Compulsory

In order to compile EXC (in any Unix-like machine), you need to provide it with some external linear algebra libraries, like LAPACK+BLAS, or ATLAS, MKL, etc. (http://www.netlib.org)

• Recommended

EXC also needs to perform Fourier transformations. This is accomplished by the provided Goedecker-FFT. However, the use of the (free) FFTW3 package is highly recommended. (http://www.fftw.org)

• Propaedeutics
• Ground state file

Abinit kss output file; interface with the CP (developed by Lucia and Giovanni) qplda output file is provided as well.

• Screening and gw corrections (if necessary)

Abinit scr,gw output file or GW (developed by Rex Godby, Lucia, Giovanni and Valerio) em1,gw file.

 Body: The new version of EXC is available. In particular the finite momentum transfer has been implemented. Body: A new version of the code has been released: v3.1. Few changes and some bug corrections for this intermediate release. Body: A new version of the code has been released: v3.0. Body: Electronic excitations are probed by experimental techniques such as optical absorption, EELS and photo-emission (direct or inverse). Body: Theoretical Spectroscopy Lectures: Theory and Codes