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Many-body perturbation theory using the density-functional concept: beyond the GW approximation.
Fabien Bruneval1, Francesco Sottile, Valerio Olevano
1Laboratoire des Solides Irradiés, UMR 7642 CNRS/CEA, Ecole Polytechnique, 91128 Palaiseau, France.
Physical Review Letters
|May 21, 2005
Summary
We present a new formulation of many-body perturbation theory using density-functional theory. This approach simplifies calculations and improves optical absorption and energy-loss spectra for materials science.
Area of Science:
- Condensed matter physics
- Quantum chemistry
- Materials science
Background:
- Many-body perturbation theory (MBPT) is crucial for understanding electronic properties.
- Traditional MBPT methods often involve complex calculations, such as four-point integral equations for polarizability.
Purpose of the Study:
- To introduce a novel, simplified formulation of MBPT.
- To demonstrate the advantages of this new approach for calculating electronic spectra and self-energy corrections.
Main Methods:
- Developed an alternative MBPT formulation based on the density-functional concept.
- Replaced the four-point integral equation for polarizability with a two-point one.
- Utilized integration for calculating vertex functions and self-energy at any approximation level.
Main Results:
- Achieved excellent optical absorption and energy-loss spectra.
- Demonstrated a direct impact on time-dependent density-functional theory.
- Illustrated corrections beyond the GW approximation for the self-energy in silicon and argon.
Conclusions:
- The proposed density-functional-based MBPT formulation offers a more efficient and accurate method.
- This approach provides valuable insights into electronic properties and band gaps.
- The method shows promise for advancing materials modeling and prediction.