Coulson–Fischer theory Generalized valence bond Modern valence bond theory
Molecular orbital theory
Hartree–Fock method Semi-empirical quantum chemistry methods Møller–Plesset perturbation theory Configuration interaction Coupled cluster Multi-configurational self-consistent field Quantum chemistry composite methods Quantum Monte Carlo
Density functional theory
Time-dependent density functional theory Thomas–Fermi model Orbital-free density functional theory Linearized augmented-plane-wave method Projector augmented wave method
Electronic band structure
Nearly free electron model Tight binding Muffin-tin approximation k·p perturbation theory Empty lattice approximation GW approximation Korringa–Kohn–Rostoker method
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The GW approximation (GWA) is an approximation made in order to calculate the self-energy of a many-body system of electrons.[1][2][3] The approximation is that the expansion of the self-energy Σ in terms of the single particle Green's function G and the screened Coulomb interaction W (in units of )
can be truncated after the first term:
In other words, the self-energy is expanded in a formal Taylor series in powers of the screened interaction W and the lowest order term is kept in the expansion in GWA.
^Hedin, Lars (1965). "New Method for Calculating the One-Particle Green's Function with Application to the Electron-Gas Problem". Phys. Rev. 139 (3A): A796–A823. Bibcode:1965PhRv..139..796H. doi:10.1103/PhysRev.139.A796. S2CID 73720887.
^Aulbur, Wilfried G.; Jönsson, Lars; Wilkins, John W. (2000). "Quasiparticle Calculations in Solids". Solid State Physics. 54: 1–218. doi:10.1016/S0081-1947(08)60248-9. ISBN 9780126077544. ISSN 0081-1947.
^Aryasetiawan, F; Gunnarsson, O (1998). "The GW method". Reports on Progress in Physics. 61 (3): 237–312. arXiv:cond-mat/9712013. Bibcode:1998RPPh...61..237A. doi:10.1088/0034-4885/61/3/002. ISSN 0034-4885. S2CID 119000468.
The GWapproximation (GWA) is an approximation made in order to calculate the self-energy of a many-body system of electrons. The approximation is that...
complex quantity and usually approximations are needed to solve the problem. One such approximation is the GWapproximation, so called from the mathematical...
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enough for calculations in quantum chemistry until the 1990s, when the approximations used in the theory were greatly refined to better model the exchange...
about strongly correlated material the tight binding approach is basic approximation because highly localized electrons like 3-d transition metal electrons...
The model is closely related to the more conceptual empty lattice approximation. The model enables understanding and calculation of the electronic band...
molecular orbitals—as linear combinations of atomic orbitals (LCAO). These approximations are made by applying the density functional theory (DFT) or Hartree–Fock...
these approaches is to provide a reliable solution (or an accurate approximation) of the quantum many-body problem. The diverse flavors of quantum Monte...
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electron model Tight binding Muffin-tin approximation k·p perturbation theory Empty lattice approximationGWapproximation Korringa–Kohn–Rostoker method v t...
functions. The PAW method is typically combined with the frozen core approximation, in which the core states are assumed to be unaffected by the ion's...
within the Born–Oppenheimer approximation (although schemes have also been drawn up to work without the BO approximation). One possible improvement to...
the nonrelativistic Schrödinger equation within the Born–Oppenheimer approximation for a quantum chemical multi-electron system. Mathematically, configuration...
The empty lattice approximation is a theoretical electronic band structure model in which the potential is periodic and weak (close to constant). One...
electron model Tight binding Muffin-tin approximation k·p perturbation theory Empty lattice approximationGWapproximation Korringa–Kohn–Rostoker method v t...
approximation, or real-axis Lifetimes within the GWapproximation Optical absorption: RPA, Bethe Salpeter with or without Tamm-Dancoff approximation,...
optimization and frequency calculation. Additionally, the frozen-core approximation is made for the initial MP2 optimization, whereas G2 usually uses the...
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