This guide gives a general overview of the contents and of the installation of QUANTUM ESPRESSO (opEn-Source Package for Research in Electronic Structure, Simulation, and Optimization), version 6.4.1.

*Important notice: due to the lack of time and of manpower, this
manual does not cover many important aspects and may contain outdated
information.*

The QUANTUM ESPRESSO distribution contains the core packages `PWscf` (Plane-Wave
Self-Consistent Field) and `CP` (Car-Parrinello) for the calculation
of electronic-structure properties within
Density-Functional Theory (DFT), using a Plane-Wave (PW) basis set
and pseudopotentials. It also includes other packages for
more specialized calculations:

`PWneb`: energy barriers and reaction pathways through the Nudged Elastic Band (NEB) method.`PHonon`: vibrational properties with Density-Functional Perturbation Theory (DFPT).`PostProc`: codes and utilities for data postprocessing.`PWcond`: ballistic conductance.`XSPECTRA`: K-, L_{1}-, L_{2, 3}-edge X-ray absorption spectra.`TD-DFPT`: spectra from Time-Dependent Density-Functional Perturbation Theory.`GWL`: electronic excitations within the GW approximation and with the Bethe-Salpeter Equation`EPW`: calculation of the electron-phonon coefficients and related quantities;`HP`: calculation of Hubbard*U*parameters using DFPT.

`PWgui`: a Graphical User Interface, producing input data files for`PWscf`and some`PostProc`codes.`atomic`: atomic calculations and pseudopotential generation.

`Wannier90`: maximally localized Wannier functions.`WanT`: quantum transport properties with Wannier functions.`YAMBO`: electronic excitations within Many-Body Perturbation Theory, GW and Bethe-Salpeter equation.`PLUMED`(v.1.3 only): calculation of free-energy surface through metadynamics.`GIPAW`(Gauge-Independent Projector Augmented Waves): NMR chemical shifts and EPR g-tensor.

Documentation on single packages can be found in the `Doc/`
directory of each package. A detailed description of input
data is available for most packages in files `INPUT_*.txt` and
`INPUT_*.html`.

The QUANTUM ESPRESSO codes work on many different types of Unix machines,
including parallel machines using both OpenMP and MPI
(Message Passing Interface).
QUANTUM ESPRESSO also runs on Mac OS X and MS-Windows machines
(see section 2.2). A GPU-enabled version is
available on `https://github.com/fspiga/qe-gpu`.

Further documentation, beyond what is provided in this guide, can be found in:

- the
`Doc/`and`examples/`directories of the QUANTUM ESPRESSO distribution; - the web site
`www.quantum-espresso.org`; - the archives of the mailing list: See section 1.2, ``Contacts'', for more info.

This guide does not explain the basic Unix concepts (shell, execution
path, directories etc.) and utilities needed to run QUANTUM ESPRESSO; it does not
explain either solid state physics and its computational methods.
If you want to learn the latter, you should first read a good textbook,
such as e.g. the book by Richard Martin:
*Electronic Structure: Basic Theory and Practical Methods*,
Cambridge University Press (2004); or:
*Density functional theory: a practical introduction*,
D. S. Sholl, J. A. Steckel (Wiley, 2009); or
*Electronic Structure Calculations for Solids and Molecules:
Theory and Computational Methods*,
J. Kohanoff (Cambridge University Press, 2006). Then you should consult
the documentation of the package you want to use for more specific references.

All trademarks mentioned in this guide belong to their respective owners.