Unphysical discontinuities, intruder states and regularization in <i>GW</i> methods
Enzo Monino, Pierre‐François Loos
Abstract
By recasting the non-linear frequency-dependent GW quasiparticle equation into a linear eigenvalue problem, we explain the appearance of multiple solutions and unphysical discontinuities in various physical quantities computed within the GW approximation. Considering the GW self-energy as an effective Hamiltonian, it is shown that these issues are key signatures of strong correlation in the (N ± 1)-electron states and can be directly related to the intruder state problem. A simple and efficient regularization procedure inspired by the similarity renormalization group is proposed to avoid such issues and speed up the convergence of partially self-consistent GW calculations.
Topics & Concepts
Classification of discontinuitiesEigenvalues and eigenvectorsRegularization (linguistics)Hamiltonian (control theory)QuasiparticleRenormalizationPhysicsMathematicsMathematical physicsQuantum mechanicsApplied mathematicsMathematical analysisComputer scienceMathematical optimizationSuperconductivityArtificial intelligencePhysics of Superconductivity and MagnetismSurface and Thin Film PhenomenaAdvanced Chemical Physics Studies