This tool provides an introduction to many-body perturbation theory within the GW approximation as a method to compute the electronic structure of materials including exchange and correlation effects beyond those in standard density functional theory (DFT), such as the local density approximation, the generalized gradient approximation, or even hybrid functionals. Here, quasiparticle excitation energies are computed as a first-order correction to Kohn-Sham eigenvalues. This method has been established to predict quasiparticle excited state energies and related quantities, such as band gaps and bandwidths, with good accuracy for a variety of inorganic semiconductors, insulators, and metals. Recently, the GW approximation has also been applied to the study of molecular systems.
This tool contains two examples: bulk silicon and a gas-phase benzene molecule. It allows the user to calculate the quasiparticle band structure for the former and the molecular orbital energies of the latter. For both examples, the user can vary the convergence parameters and explore how they affect the accuracy.
Berkeley GW, Quantum Espresso 4.1, WANNIER90
The Berkeley GW code is implemented by the Cohen/Louie group at UC Berkeley. See http://www.berkeleygw.org/.
Lawrence Berkeley National Laboratory and The Molecular Foundry (http://foundry.lbl.gov/)
Hybertsen and Louie, "Electron correlation in semiconductors and insulators: Band gaps and quasiparticle energies," Phys. Rev. B 34,5390(1986); P. Giannozzi, et al. "QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials," J. Phys. Condens. Matter 21, 395502 (2009); A. A. Mostofi, J. R. Yates, Y.-S. Lee, I. Souza, D. Vanderbilt and N. Marzari, "Wannier90: A Tool for Obtaining Maximally-Localised Wannier Functions," Comput. Phys. Commun. 178, 685 (2008).
Cite this work
Researchers should cite this work as follows: