Center for Molecular Modeling - Y. Dewulf

Nuclear overlap functions determined by the asymptotic behavior of the one-body density matrix

wim — Mon, 26 Nov 2012 08:16:36 +0000

D. Van Neck, L. Van Daele, Y. Dewulf, M. Waroquier

Physical Review C

56 (3), 1398-1409

1997

Published while none of the authors were employed at the CMM

Abstract

Single-particle overlap functions and spectroscopic factors are calculated using the asymptotic behavior in coordinate space of the one-body density matrix corresponding to a many-body wave function in correlated basis function theory. We include state-dependent correlation functions and discriminate between the effects of central, spin-spin, and tensor correlations. The method is applied to ¹⁶O. We also discuss the effect of center-of-mass motion on the calculated spectroscopic factors.

DOI

http://dx.doi.org/10.1103/PhysRevC.56.1398

Long-range correlations in finite nuclei: comparison of two self-consistent treatments

wim — Mon, 26 Nov 2012 08:13:33 +0000

Y. Dewulf, D. Van Neck, L. Van Daele, M. Waroquier

Physics Letters B

396, 7-14

1997

Published while none of the authors were employed at the CMM

Abstract

Long-range correlations, which are partially responsible for the observed fragmentation and depletion of low-lying single-particle strength, are studied in the Green's function formalism. The self-energy is expanded up to second order in the residual interaction. We compare two methods of implementing self-consistency in the solution of the Dyson equation beyond Hartree-Fock, for the case of the 16O nucleus. It is found that the energy-bin method and the BAGEL method lead to globally equivalent results. In both methods the final single-particle strength functions are characterized by exponential tails at energies far from the Fermi level.

DOI

http://dx.doi.org/10.1016/S0370-2693(97)00135-4

Nuclear equation of state and the structure of neutron stars

wim — Mon, 03 Oct 2011 13:23:16 +0000

A.E.L. Dieperink, D. Van Neck, Y. Dewulf, V. Rodin

Nato Science series: Superdense QCD Matter and Compact Stars

20 (1), 1742-6588 | ISSN 1742-6588 (Print) ISSN 1742-6596 (Online)

2006

Abstract

The hadronic equation of state for a neutron star is discussed with a particular emphasis on the symmetry energy. The results of several microscopic approaches are compared and also a new calculation in terms of the self-consistent Green function method is presented. In addition possible constraints on the symmetry energy coming from empirical information from the neutron skin of finite nuclei are considered. | Invited talk presented at the Advanced Research Workshop on "Superdense QCD Matter and Compact Stars", Yerevan, Armenia, Sep 27 2003

DOI

http://arXiv:nucl-th/0312012v1

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0312012v1.pdf

Discrete approach to self-consistent GW calculations in an electron gas

wim — Fri, 30 Sep 2011 13:33:32 +0000

Y. Dewulf, D. Van Neck, M. Waroquier

Physical Review B

71 (24),245122

2005

Abstract

Recent debate considering the importance of combining the GW approach to the electron gas with vertex corrections urges a calculation that can deal with both concepts in a self-consistent way. A major difficulty is the complicated energy dependence of the electron spectral function. We therefore propose an approximation for the Green’s function that may be very useful for tackling a more complete treatment of the electron gas problem. The key concept in this approach is the representation of the Green’s function by a limited number of carefully chosen poles. In this paper we present results for self-consistent GW calculation and find that they compare quite well to other self-consistent approaches. This legitimizes the use of this scheme as a practical tool for more involved calculations.

DOI

http://dx.doi.org/10.1103/PhysRevB.71.245122

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05 physrev B 71(24)245122 dewulf.pdf

Nuclear symmetry energy and the neutron skin in neutron-rich nuclei

wim — Fri, 30 Sep 2011 11:54:35 +0000

A.E.L. Dieperink, Y. Dewulf, D. Van Neck, M. Waroquier, V. Rodin

Physical Review C

68(6), 064307

2003

Abstract

The symmetry energy for nuclear matter and its relation to the neutron skin in finite nuclei is discussed. The symmetry energy as a function of density obtained in a self-consistent Green function approach is presented and compared to the results of other recent theoretical approaches. A partial explanation of the linear relation between the symmetry energy and the neutron skin is proposed. The potential of several experimental methods to extract the neutron skin is examined.

DOI

http://dx.doi.org/10.1103/PhysRevC.68.064307

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03 phys. rev. C 68(6)064307 dieperink.pdf

Saturation of Nuclear Matter and Short-Range Correlations

wim — Fri, 30 Sep 2011 11:50:05 +0000

Y. Dewulf, W.H. Dickhoff, D. Van Neck, E.R. Stoddard, M. Waroquier

Physical Review Letters

90 (15), 152501

2003

Abstract

A fully self-consistent treatment of short-range correlations in nuclear matter is presented. Different implementations of the determination of the nucleon spectral functions for different interactions are shown to be consistent with each other. The resulting saturation densities are closer to the empirical result when compared with (continuous choice) Brueckner-Hartree-Fock values. Arguments for the dominance of short-range correlations in determining the nuclear matter saturation density are presented. A further survey of the role of long-range correlations suggests that the inclusion of pionic contributions to ring diagrams in nuclear matter leads to higher saturation densities than empirically observed. A possible resolution of the nuclear matter saturation problem is suggested.

DOI

http://dx.doi.org/10.1103/PhysRevLett.90.152501

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03 phys rev lett 90(15)152501 dewulf.pdf

Effects of self-consistency in a Green’s function description of saturation in nuclear matter

wim — Fri, 30 Sep 2011 09:53:01 +0000

Y. Dewulf, D. Van Neck, M. Waroquier

Physical Review C

65(5), 054316

2002

Abstract

The binding energy in nuclear matter is evaluated within the framework of self-consistent Green’s function theory, using a realistic nucleon-nucleon interaction. The two-body dynamics is solved at the level of summing particle-particle and hole-hole ladders. We go beyond the on-shell approximation and use intermediary propagators with a discrete-pole structure. A three-pole approximation is used, which provides a good representation of the quasiparticle excitations, as well as reproducing the zeroth- and first-order energy-weighted moments in both the nucleon removal and addition domains of the spectral function. Results for the binding energy are practically independent of the details of the discretization scheme. The main effect of the increased self-consistency is to introduce an additional density dependence, which causes a shift towards lower densities and smaller binding energies, as compared to a (continuous choice) Brueckner calculation with the same interaction. Particle number conservation and the Hugenholz–Van Hove theorem are satisfied with reasonable accuracy.

DOI

http://dx.doi.org/10.1103/PhysRevC.65.054316

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02 phys. rev. C 65(5)054316 dewulf.pdf

Improved lower bounds for the ground-state energy of many-body systems

wim — Fri, 30 Sep 2011 09:04:07 +0000

D. Van Neck, Y. Dewulf, M. Waroquier

Physical Review A

63, 062107

2001

Abstract

Alternative lower bounds for the binding energy of a quantum-mechanical system of interacting particles are presented. These bounds are expressed in terms of two-particle quantities and improve the conventional bounds of the Hall-Post type. They are constructed by considering not only the energy in the two-particle system, but also the structure of the pair wave function. We apply the formal results to various numerical examples, and show that in some cases dramatic improvement over the existing bounds is reached.

DOI

http://dx.doi.org/10.1103/PhysRevA.63.062107

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01 phys. rev. A 63(6)062107 van neck.pdf

Short-range correlations in muclear matter using Green's functions within a discrete pole approximation

wim — Fri, 30 Sep 2011 09:01:47 +0000

Y. Dewulf, D. Van Neck, M. Waroquier

Physics Letters B

510 (1-4), 89-97

2001

Abstract

We treat short-range correlations in nuclear matter, induced by the repulsive core of the nucleon–nucleon potential, within the framework of self-consistent Green's function theory. The effective in-medium interaction sums the ladder diagrams of both the particle–particle and hole–hole type. The demand of self-consistency results in a set of nonlinear equations which must be solved by iteration. We explore the possibility of approximating the single-particle Green's function by a limited number of poles and residues.

DOI

http://dx.doi.org/10.1016/S0370-2693(01)00560-3

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01 phys. lett. 510(1-4)89 dewulf.pdf

Short-range correlations in nuclear matter using Green's functions within a discrete pole approximation

wim — Tue, 18 Oct 2011 08:56:02 +0000

Y. Dewulf, D. Van Neck, M. Waroquier

Poster

Conference / event / venue

The International Conference in Many-Body Theories

Manchester, UK

Monday, 9 July, 2001 to Friday, 13 July, 2001