The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Quantum ESPRESSO (QE) is a free, open-source suite for calculating electronic structure and modelling materials. Its core methods use density functional theory (DFT), plane-wave basis sets and pseudopotentials. It is not a single all-purpose program: pw.x is the main entry point for many electronic-structure calculations, while separate QE packages handle tasks such as phonons, reaction pathways, spectra and post-processing.
What Quantum ESPRESSO does
QE’s core codes calculate electronic-structure properties within DFT using plane waves and pseudopotentials. In broad terms, a calculation represents a material’s atomic structure, uses a selected pseudopotential for each element, and solves for electronic properties under the chosen computational settings. The result depends on the suitability of those choices for the scientific question; using QE does not by itself guarantee a reliable method or answer.
The suite includes PWscf (plane-wave self-consistent-field) and CP (Car–Parrinello), along with specialist programs. The main executable for PWscf calculations is pw.x. Other tasks use their corresponding packages and workflows rather than one universal QE command.
Which QE package fits which task?
| Research task | QE package or tool | Role |
|---|---|---|
| Plane-wave self-consistent-field electronic-structure calculations | PWscf (pw.x) |
Core DFT calculations using plane waves and pseudopotentials. |
| Car–Parrinello calculations | CP | A separate core package in the QE distribution. |
| Reaction pathways and energy barriers | PWneb | Nudged-elastic-band calculations. |
| Vibrational properties | PHonon | Density-functional perturbation theory calculations. |
| Analysis of results | PostProc utilities | Post-processing tasks using QE outputs. |
| Ballistic conductance | PWcond | Calculations of ballistic conductance. |
| X-ray absorption spectra | XSPECTRA | Spectra calculations. |
| Spectra using time-dependent density-functional perturbation theory | TDDFPT | Time-dependent density-functional perturbation theory calculations. |
| GW and Bethe–Salpeter calculations | GWL | Many-body perturbation and related calculations. |
| Electron-phonon coefficients and related transport or optical calculations | EPW | Electron-phonon calculations and related properties. |
| Hubbard U parameters | HP | Calculations of Hubbard U parameters. |
| Energy-current and thermal-transport calculations | QEHeat | Energy-current and thermal-transport calculations. |
| Atomic calculations and pseudopotential generation | atomic |
Auxiliary atomic code. |
| Creating input files through a graphical interface | PWgui | Generates input files; it does not remove the need to check their settings. |
QE documentation also names Wannier90, WanT, YAMBO, D3Q, GIPAW and PLUMED in its broader ecosystem. These are related tools, not interchangeable names for QE’s core packages; whether they are available in a particular installation depends on the tool and build.
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How to get started with a QE calculation
1. Choose a version and installation route
The version 7.5.0 User’s Guide 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; the guide also describes selected binary packages and virtual-machine options, whose availability may vary.
The guide documents builds using both CMake and make, and discusses numerical libraries and parallel builds. The appropriate route depends on your operating system, available compilers and libraries, and whether you need a serial or parallel build.
2. Prepare the structure and pseudopotentials
Gather the atomic structure and an appropriate pseudopotential for each element. Pseudopotential choice is part of the scientific method, not just an installation detail: record which files and versions you use, and verify that they suit the calculation you intend to perform.
3. Create and review the input
For a PWscf calculation, prepare a pw.x input file. You can write it by hand or generate it with PWgui. In the input, pseudo_dir specifies the directory containing pseudopotential files, while outdir specifies where input, temporary and output files are kept. Check the official pw.x input description for the parameters and their meanings.
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The official guide’s examples and test suite are useful templates for learning input structure and expected workflows. They are not automatically validated for your material or research question: review and adapt their structures, pseudopotentials, computational settings and convergence criteria.
4. Run the calculation and assess it
Run the appropriate QE executable with the input you prepared; for a PWscf calculation, that is pw.x. Afterward, inspect the output for errors and whether the calculation reached its intended stopping condition. Use the relevant post-processing tools for the property you need, then assess whether the numerical settings are sufficiently converged and scientifically appropriate. A successful run is not, on its own, evidence that the result answers the research question.
Platforms, parallel computing and GPUs
The version 7.5.0 guide describes support across multiple Unix systems, macOS and Windows. It also documents parallel computing with MPI and OpenMP. Actual build options and performance depend on the system, compiler, libraries and configuration.
For accelerators, the same guide says NVIDIA GPUs are supported by stable releases, while AMD GPU support was not in the main repository and stable releases it describes. These statements are tied to that guide and release context; they are not a guarantee that a GPU is supported by every QE version, operating system or binary package. Check current version-specific documentation before planning a build around a particular accelerator.
Reproducibility and citations
Quantum ESPRESSO’s official guide states: “Quantum ESPRESSO is free software, released under the GNU General Public License.” For a textual citation of the code, it advises: “Note the form Quantum ESPRESSO for textual citations of the code.”
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The guide requests acknowledgment of the QE publications by Giannozzi and colleagues in the Journal of Physics: Condensed Matter from 2009 and 2017. It also points users to package-specific citation recommendations and says to cite the pseudopotentials used. For reproducibility, report the QE version, functional, pseudopotentials and relevant computational settings actually used, in addition to the citations requested for the packages and methods in your calculation.
Where to learn the underlying theory
The official guide recommends Richard M. Martin’s Electronic Structure: Basic Theory and Practical Methods as background reading on solid-state physics and computational methods. It is optional theory-focused reading, not a QE manual or a prerequisite for installing the software.
Quick Recap
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