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Quantum ESPRESSO (QE) is a free, open-source suite for calculating electronic structure and modelling materials. Its core plane-wave codes use density-functional theory (DFT) and pseudopotentials, while separate packages handle tasks such as phonons, reaction pathways, spectra and post-processing. The main self-consistent-field entry point is pw.x (PWscf); QE is a collection of programs, not a single black-box application.
What Quantum ESPRESSO does
QE calculates electronic-structure properties within DFT using plane-wave basis sets and pseudopotentials. In practical terms, you describe a system—such as a crystal, molecule or other atomic structure—and provide calculation settings and pseudopotential files. The code then solves the specified computational problem. The result depends on the chosen method and settings; the software itself does not guarantee that a model is appropriate for a particular scientific question.
The distribution includes distinct programs for different stages and kinds of simulation. pw.x, also known as PWscf, is the principal plane-wave self-consistent-field program. Other packages extend the suite to specialized calculations and analysis.
Which QE package fits the task?
| Research task | QE package or program | Role |
|---|---|---|
| Plane-wave self-consistent-field calculations | PWscf (pw.x) |
Core DFT calculations using plane waves and pseudopotentials. |
| Car-Parrinello simulations | CP | Car-Parrinello molecular-dynamics package. |
| Reaction pathways and energy barriers | PWneb | Nudged-elastic-band calculations. |
| Vibrational properties | PHonon | Density-functional perturbation theory calculations. |
| Post-processing and analysis | PostProc | Utilities for processing QE results. |
| Ballistic conductance | PWcond | Conductance calculations. |
| X-ray absorption spectra | XSPECTRA | Spectra calculations. |
| Spectra calculations | TDDFPT | Time-dependent density-functional perturbation theory tools. |
| GW and Bethe–Salpeter calculations | GWL | Tools for these many-body calculations. |
| Electron-phonon properties, transport and optical calculations | EPW | Electron-phonon coefficients and related calculations. |
| Hubbard U parameters | HP | Tools for calculating Hubbard parameters. |
| Energy current and thermal transport | QEHeat | Calculations related to energy-current and thermal-transport properties. |
| Atomic calculations and pseudopotential generation | atomic |
Auxiliary atomic code, including pseudopotential generation. |
| Creating input files | PWgui | Graphical tool for producing PW input files. |
QE materials also describe a broader ecosystem that includes Wannier90, WanT, YAMBO, D3Q, GIPAW and PLUMED. These are related tools, not necessarily identical to the core QE distribution or automatically installed with it; check the documentation and build instructions for the particular tool you need.
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Getting started with a QE calculation
The official User’s Guide reviewed here is version 7.5.0 and identifies 7.5.0 as the current stable release. Release status can change, so check the official download page before choosing a version. QE is distributed as source code; selected binaries and virtual-machine options may also be available. The guide documents source builds using both CMake and make.
- Choose a release and build route. Start with the official versioned User’s Guide and download information. Account for the numerical libraries and parallel configuration your intended build requires.
- Prepare the system definition. Define the atoms and structure relevant to the question you want to study. Choose pseudopotentials that are appropriate for the elements and methods in the calculation; the input and pseudopotential choices are part of the scientific model, not just setup details.
- Create a PW input file. You can write the input by hand or generate it with PWgui. In the
pw.xinput,pseudo_dirpoints to the directory containing pseudopotential files, whileoutdirspecifies where input, temporary and output files are stored. - Run
pw.xand inspect the result. Follow the PWscf usage documentation for the run you intend to perform. Review the output for completion, convergence and the settings actually applied rather than treating a finished run as proof that the model is scientifically adequate. - Use task-specific tools for later stages. Select the relevant package for phonons, pathways, spectra or other analyses, then use PostProc utilities where appropriate. Check package-specific documentation because requirements and workflows differ.
The guide’s examples and test suite can help you learn input syntax and build a starting point. They are templates, not validation that an example’s structure, pseudopotentials, convergence settings or approximations fit your own research question. Adapt and check every consequential setting.
Platforms, parallel builds and GPU support
The version 7.5.0 guide describes support on multiple Unix systems, macOS and Windows, and discusses parallel execution with MPI and OpenMP. It also states that NVIDIA GPUs are supported by stable releases covered by the guide, while AMD GPU support was not in the main repository and stable releases it describes. These are version-specific documentation statements, not guarantees for every platform, build, package or hardware configuration. Check the current guide and build requirements for the release and installation route you plan to use.
How to cite Quantum ESPRESSO and report a calculation
QE is free software released under the GNU General Public License. For textual references, the official guide says: “Note the form Quantum ESPRESSO for textual citations of the code.” It requests acknowledgment of the Quantum ESPRESSO papers by Giannozzi and colleagues in Journal of Physics: Condensed Matter (2009 and 2017). Consult the package-specific citation recommendations as well, and cite the pseudopotentials used.
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For a reproducible report, identify the QE version, exchange-correlation functional, pseudopotential files and relevant computational settings actually used. Include enough detail for readers to understand the model and assess whether the calculation addresses the stated question.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Where to learn the underlying theory
If you need foundations in solid-state physics and computational methods, the official guide recommends Richard M. Martin’s Electronic Structure: Basic Theory and Practical Methods. It is optional background reading, not a QE manual or a prerequisite for installing the software.
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