Center for Molecular Modeling - C. Barbieri

Accuracy of the Faddeev random phase approximation for light atoms

wim — Fri, 03 Feb 2012 08:47:03 +0000

C. Barbieri, D. Van Neck, M. Degroote

Physical Review A

85 (1) 012501

2012

Abstract

The accuracy of the Faddeev random phase approximation (FRPA) method is tested by evaluating total and ionization energies in the basis-set limit. A set of light atoms up to Ar is considered. Comparisons are made with the results of coupled-cluster singles and doubles (CCSD), with third-order algebraic diagrammatic construction [ADC(3)], and with the experiment. It is seen that even for two-electron systems, He and Be(2+), the inclusion of RPA effects leads to satisfactory results, and therefore it does not overcorrelate the ground state. The FRPA becomes progressively better for larger atomic numbers, where it gives approximate to 5 mH more correlation energy, and it shifts ionization potentials by 2-10 mH with respect to the similar ADC(3) method. The ionization potentials from FRPA tend to reduce the discrepancies with the experiment.

Open Access version available at UGent repository

DOI

http://dx.doi.org/10.1103/PhysRevA.85.012501

Private attachment

12 phys. rev. A 85(1)012501 Barbieri.pdf

Faddeev random phase approximation for molecules

wim — Fri, 20 Jan 2012 14:20:41 +0000

M. Degroote, D. Van Neck, C. Barbieri

Computer Physics Communications

182 (9) 1995-1998

2011

Abstract

This paper presents the problem of Molecular Beam Epitaxy and Reflection High-Energy Electron Diffraction with the help of a unified, modern MDA approach. Model-Driven Architecture (MDA) constitutes a modern and unusually efficient method of improving the process of generating software. It was created at the beginning of the twenty-first century by the Object Management Group as an element of Model-Driven Development, a highly promoted trend in software engineering. In MDA a viewpoint on a system is a technique for abstraction using a selected set of architectural concepts and structuring rules, in order to focus on particular concerns within a system. In MDA, system design begins with defining the problem domain. Next, at a highly abstract level independent of the system and programming platform a Platform-Independent Model (PIM) is constructed as well as a general system specification. This specification is created with the help of Unified Modeling Language. The real implementation of the system is performed through the transformation of PIM to Platform-Specific Model (PSM). The essence of Model-Driven Architecture is the replacement of the twentieth century approach to programming, calling that "everything is an object, to the modern "everything is a model". (C) 2011 Elsevier B.V. All rights reserved.

Open Access version available at UGent repository

DOI

http://dx.doi.org/10.1016/j.cpc.2010.10.024

Private attachment

11 comp. phys. comm. 182,1995 degroote.pdf

Ab-initio Green's Functions Calculations of Atoms

wim — Mon, 03 Oct 2011 10:13:21 +0000

C. Barbieri, D. Van Neck

AIP Conference Proceedings

1120, 104-108

2009

Abstract

The Faddeev random phase approximation (FRPA) method is applied to calculate the ground state and ionization energies of simple atoms. First ionization energies agree with the experiment at the level of ~10 mH or less. Calculations with similar accuracy are expected to provide information required for developing the proposed quasiparticle-DFT method. ©2009 American Institute of Physics

DOI

http://dx.doi.org/10.1063/1.3141630

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09 persp. nuclear phys. 1120, 104 barbieri.pdf

Faddeev random-phase approximation for molecules

wim — Mon, 22 Aug 2011 14:28:50 +0000

M. Degroote, D. Van Neck, C. Barbieri

Physical Review A

83, 042517

2011

Abstract

The Faddeev random-phase approximation is a Green’s function technique that makes use of Faddeev equations to couple the motion of a single electron to the two-particle–one-hole and two-hole–one-particle excitations. This method goes beyond the frequently used third-order algebraic diagrammatic construction method: all diagrams involving the exchange of phonons in the particle-hole and particle-particle channel are retained, but the phonons are now described at the level of the random-phase approximation, which includes ground-state correlations, rather than at the Tamm-Dancoff approximation level, where ground-state correlations are excluded. Previously applied to atoms, this paper presents results for small molecules at equilibrium geometry. © 2011 American Physical Society

Open Access version available at UGent repository

DOI

http://dx.doi.org/10.1103/PhysRevA.83.042517

Private attachment

11 phys rev A 83, 042517 degroote.pdf

Faddeev Random Phase Approximation for Molecules

wim — Thu, 20 Oct 2011 14:34:04 +0000

M. Degroote, D. Van Neck, C. Barbieri

p. 255

Poster

Conference / event / venue

ISTCP-VII

Waseda, Japan

Friday, 2 September, 2011 to Saturday, 8 October, 2011

Abstract

201109AbstractJapanMD.pdf

Conference reference

ISTCP-VII