S. Verdonck

Characterization of the electron propagator with a GW-like self-energy in closed-shell atoms

S. Verdonck, D. Van Neck, P.W. Ayers, M. Waroquier
Physical Review A
74 (6), 062503
2006
A1

Abstract 

The electron propagator is calculated for a set of closed-shell atoms using GW-like self-energies that contain the coupling of single-particle degrees of freedom with excited states in the framework of the random phase approximation. The effect of including exchange diagrams is investigated. Calculations are performed in the Hartree-Fock (HF) basis of the neutral atom. The HF continuum is taken into account using a discretization procedure, and the basis set limit is estimated using a systematic increase of basis set size. We check the approximation of taking the self-energy diagonal in the HF basis, and to what extent the extended Koopman’s theorem is fulfilled using an approximate self-energy. Finally we try to model the information contained in the propagator in terms of a functional containing Hartree-Fock quantities and demonstrate the feasibility of simultaneously reproducing the correlation and ionization energy of an underlying ab initio model.

Quasiparticle properties in a density-functional framework

D. Van Neck, S. Verdonck, G. Bonny, P.W. Ayers, M. Waroquier
Physical Review A
74 (4), 042501
2006
A1

Abstract 

We propose a framework to construct the ground-state energy and density matrix of an N-electron system by solving a self-consistent set of single-particle equations. The method can be viewed as a nontrivial extension of the Kohn-Sham scheme (which is embedded as a special case). It is based on separating the Green’s function into a quasiparticle part and a background part, and expressing only the background part as a functional of the density matrix. The calculated single-particle energies and wave functions have a clear physical interpretation as quasiparticle energies and orbitals.

Spectral functions in an exactly solvable self-bound A-body system

D. Van Neck, S. Rombouts, S. Verdonck
Physical Review C
72 (5), 054318
2005
A1

Abstract 

We consider an exactly solvable Hamiltonian for bosons in one-dimension interacting through zero-range attractive forces, and construct a complete basis of its A-particle eigenstates. The structure of the single-particle spectral function in the removal domain is investigated, by taking the overlap of the A-particle ground state with the various excited states of the (A-1) system. In particular we study the contribution to the spectral function of the different break-up channels in the A-1 continuum, and compare the results to general statements available in the literature. It is shown that the asymptotic behavior in coordinate space does not agree with conventional assumptions. The relation to recent (e,e'p) experiments at large values of missing energy and momentum is pointed out.

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