Quantum ESPRESSO is a software suite for ab initio quantum chemistry methods of electronic-structure calculation and materials modeling, distributed for free under the GNU General Public License. It is based on Density Functional Theory, plane wave basis sets, and pseudopotentials (both norm-conserving and ultrasoft). ESPRESSO is an acronym for opEn-Source Package for Research in Electronic Structure, Simulation, and Optimization. 
The core plane wave DFT functions of QE are provided by the PWscf component, PWscf previously existed as an independent project. PWscf (Plane-Wave Self-Consistent Field) is a set of programs for electronic structure calculations within density functional theory and density functional perturbation theory, using plane wave basis sets and pseudopotentials. The software is released under the GNU General Public License.
The latest version QE-6.3.0 was released on 5 July 2018.
QUANTUM ESPRESSO Project
Quantum ESPRESSO is an open initiative, of the CNR-IOM DEMOCRITOS National Simulation Center in Trieste (Italy) and its partners, in collaboration with different centers worldwide such as MIT, Princeton University, the University of Minnesota or the Ecole Polytechnique Fédérale de Lausanne. The project is coordinated by the QUANTUM ESPRESSO foundation which is formed by many research centers and groups all over the world. The first version called pw.1.0.0, was released on 15-06-2001.
The program, written mainly in fortran-90 with some parts in C or in Fortran-77, was built out of the merging and re-engineering of different independently-developed core packages, plus a set of packages, designed to be inter-operable with the core components, which allow the performance of more advanced tasks.
The basic packages include Pwscf  which solves the self-consistent Kohn and Sham equations, obtained for a periodic solid, CP to carry out Car-Parrinello molecular dynamics, and PostProc, which allows data analysis and plotting. Regarding the additional packages, is noteworthy to point out atomic for the pseudopotential generation, PHonon package, which implements density-functional perturbation theory (DFPT) for the calculation of second- and third-order derivatives of the energy with respect to atomic displacements and NEB: for the calculation of reaction pathways and energy barriers.
The different tasks that can be performed include
- Ground state calculations.
- Structural optimization.
- Transition states and minimum energy paths.
- Response properties (DFPT), such as phonon frequencies, electron-phonon interactions and EPR and NMR chemical shifts.
- AB initio Molecular Dynamics: Car-Parrinello and Born-Oppenheimer MD.
- Spectroscopic properties.
- Quantum transport.
The main components of the QUANTUM ESPRESSO distribution are designed to exploit the architecture of today’s supercomputers characterized by multiple levels and layers of inter-processor communication . The parallelization is achieved using both MPI and OpenMP parallelization, allowing the main codes of the distribution to run in parallel on most or all parallel machines with very good performance.
- Paolo Giannozzi; Stefano Baroni; Nicola Bonini; Matteo Calandra; Roberto Car; Carlo Cavazzoni; Davide Ceresoli; Guido L Chiarotti; Matteo Cococcioni; Ismaila Dabo; Andrea Dal Corso; Stefano de Gironcoli; Stefano Fabris; Guido Fratesi; Ralph Gebauer; Uwe Gerstmann; Christos Gougoussis; Anton Kokalj; Michele Lazzeri; Layla Martin-Samos; Nicola Marzari; Francesco Mauri; Riccardo Mazzarello; Stefano Paolini; Alfredo Pasquarello; Lorenzo Paulatto; Carlo Sbraccia; Sandro Scandolo; Gabriele Sclauzero; Ari P Seitsonen; Alexander Smogunov; Paolo Umari & Renata M Wentzcovitch (2009). "QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials". Journal of Physics: Condensed Matter. 21 (39): 395502. arXiv:0906.2569. Bibcode:2009JPCM...21M5502G. doi:10.1088/0953-8984/21/39/395502. PMID 21832390.
- P. Giannozzi; O. Andreussi; T. Brumme; O. Bunau; M. Buongiorno Nardelli; M. Calandra; R. Car; C. Cavazzoni; D. Ceresoli; M. Cococcioni; N. Colonna; I. Carnimeo; A. Dal Corso; S. de Gironcoli; P. Delugas; R. A. DiStasio Jr.; A. Ferretti; A. Floris; G. Fratesi; G. Fugallo; R. Gebauer; U. Gerstmann; F. Giustino; T. Gorni; J. Jia; M. Kawamura; H.-Y. Ko; A. Kokalj; E. Küçükbenli; M. Lazzeri; M. Marsili; N. Marzari; F. Mauri; N. L. Nguyen; H.-V. Nguyen; A. Otero-de-la-Roza; L. Paulatto; S. Poncé; D. Rocca; R. Sabatini; B. Santra; M. Schlipf; A. P. Seitsonen; A. Smogunov; I. Timrov; T. Thonhauser; P. Umari; N. Vast; X. Wu & S. Baroni (2017). "Advanced capabilities for materials modelling with Quantum ESPRESSO". Journal of Physics: Condensed Matter. 29 (46): 465901. arXiv:1709.10010. Bibcode:2017JPCM...29T5901G. doi:10.1088/1361-648X/aa8f79.
- Corso, Andrea Dal (1996). "A Pseudopotential Plane Waves Program (PWSCF) and some Case Studies". Quantum-Mechanical Ab-initio Calculation of the Properties of Crystalline Materials. Lecture Notes in Chemistry. 67. Springer, Berlin, Heidelberg. pp. 155–178. doi:10.1007/978-3-642-61478-1_10. ISBN 9783540616450.