EPW: A program for calculating the electron–phonon coupling using maximally localized Wannier functions
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文摘
EPW (Electron–Phonon coupling using Wannier functions) is a program written in Fortran90 for calculating the electron–phonon coupling in periodic systems using density-functional perturbation theory and maximally localized Wannier functions. EPW can calculate electron–phonon interaction self-energies, electron–phonon spectral functions, and total as well as mode-resolved electron–phonon coupling strengths. The calculation of the electron–phonon coupling requires a very accurate sampling of electron–phonon scattering processes throughout the Brillouin zone, hence reliable calculations can be prohibitively time-consuming. EPW combines the Kohn–Sham electronic eigenstates and the vibrational eigenmodes provided by the Quantum ESPRESSO package (see Giannozzi et al., 2009 [1]) with the maximally localized Wannier functions provided by the wannier90 package (see Mostofi et al., 2008 [2]) in order to generate electron–phonon matrix elements on arbitrarily dense Brillouin zone grids using a generalized Fourier interpolation. This feature of EPW leads to fast and accurate calculations of the electron–phonon coupling, and enables the study of the electron–phonon coupling in large and complex systems.

Program summary

Program title: EPW

Catalogue identifier: AEHA_v1_0

Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEHA_v1_0.html

Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland

Licensing provisions: GNU Public License

No. of lines in distributed program, including test data, etc.: 304 443

No. of bytes in distributed program, including test data, etc.: 1 487 466

Distribution format: tar.gz

Programming language: Fortran 90

Computer: Any architecture with a Fortran 90 compiler

Operating system: Any environment with a Fortran 90 compiler

Has the code been vectorized or parallelized?: Yes, optimized for 1 to 64 processors

RAM: Heavily system dependent, as small as a few MB

Supplementary material: A copy of the “EPW/examples” directory containing the phonon binary files can be downloaded

Classification: 7

External routines: MPI, Quantum-ESPRESSO package [1], BLAS, LAPACK, FFTW. (The necessary Blas, Lapack and FFTW routines are included in the Quantum-ESPRESSO package [1].)

Nature of problem: The calculation of the electron–phonon coupling from first-principles requires a very accurate sampling of electron–phonon scattering processes throughout the Brillouin zone; hence reliable calculations can be prohibitively timeconsuming.

Solution method: EPW makes use of a real-space formulation and combines the Kohn–Sham electronic eigenstates and the vibrational eigenmodes provided by the Quantum-ESPRESSO package with the maximally localized Wannier functions provided by the wannier90 package in order to generate electron–phonon matrix elements on arbitrarily dense Brillouin zone grids using a generalized Fourier interpolation.

Running time: Single processor examples typically take 5–10 minutes.

References:

[1] P. Giannozzi, et al., J. Phys. Condens. Matter 21 (2009), 395502, http://www.quantum-espresso.org/.

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