openmaterials.ai / codes / Quantum ESPRESSO
An open-source suite of plane-wave pseudopotential codes whose ph.x was, to its authors' knowledge, the first implementation of density-functional perturbation theory.
ph.x computes the response to a lattice distortion of any wavelength at a cost proportional to that of the unperturbed system. Long-wavelength responses are inexpensive (Giannozzi 2009).
Iterative diagonalization and Broyden mixing with norm-conserving, ultrasoft or PAW pseudopotentials. LDA, GGA, DFT+U, meta-GGA and hybrid functionals (Giannozzi 2009).
Images, k-point pools, plane waves, task groups and linear algebra, each an MPI communicator. PWscf scaled to 4800 processors on 587 atoms (Giannozzi 2009).
QE-GPU v6.5 ports pw.x in CUDA Fortran. The speedup on one V100 is 1.4x for a 98-atom cell and exceeds 3x as the basis set grows (Giannozzi 2020).
Inputs are Fortran namelists. Output goes to a data directory with an XML-tagged head file (Giannozzi 2009). Interfaces reach LAMMPS and i-PI (Giannozzi 2017).
The SSSP protocol tests pseudopotentials with pw.x and ph.x on 85 elements. SSSP precision averages a Delta of 0.33 meV, rare-earth nitrides excluded (Prandini 2018).
Exact Boltzmann solutions with DFPT inputs give 3600 W/m/K for infinite natural graphene and 2000 W/m/K for graphite at room temperature. The single-mode result for graphite is 10x lower. Fugallo 2014
In graphene, boron nitride and graphane normal scattering dominates over Umklapp up to room temperature. In graphene at room temperature second sound travels of the order of 1 mm. Cepellotti 2015
QE force constants for PbTe and SnTe are long-ranged along <100>. Fourth neighbours 6 Å apart couple as strongly as first neighbours 3 Å apart. Eighth neighbours act as anti-springs. Lee 2014
Namelists plus CELL_PARAMETERS, ATOMIC_POSITIONS and ATOMIC_SPECIES with UPF files.
Self-consistent ground state. The output holds the total energy in Ry, forces and stress.
DFPT at the chosen q points. fildyn files hold dynamical matrices, Born charges, epsilon.
Fourier transform to real-space force constants, then frequencies and DOS on any mesh.
The outputs feed Wannier90, EPW, thermal2, AiiDA workflows or the i-PI driver.