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1.
2.
Doru S. Delion Peter Schuck Mitsuru Tohyama 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(2):45
The Self-Consistent RPA (SCRPA) approach is elaborated for cases with a continuouslybroken symmetry, this being the main focus of the present article. Correlations beyondstandard RPA are summed up correcting for the quasi-boson approximation in standard RPA.Desirable properties of standard RPA such as fulfillment of energy weighted sum rule andappearance of Goldstone (zero) modes are kept. We show theoretically and, for a modelcase, numerically that, indeed, SCRPA maintains all properties of standard RPA forpractically all situations of spontaneously broken symmetries. A simpler approximate formof SCRPA, the so-called renormalised RPA, also has these properties. The SCRPA equationsare first outlined as an eigenvalue problem, but it is also shown how an equivalent manybody Green’s function approach can be formulated. 相似文献
3.
P. Schuck 《Zeitschrift für Physik A Hadrons and Nuclei》1971,241(5):395-409
We present a closed expression for the exact deuteron (H3, He3) optical potential in terms of higher point Green functions. This form is well suited to study its energy dependence. Intermediate resonances due to two (three) particle phonon coupling are suggested and the coupling constants are identified with the Migdal parameters. 相似文献
4.
We calculate in a novel Thomas-Fermi theory for multiparticle-multihole states the contributions of the correlation and polarization graphs to the imaginary part of the nucleon-nucleus optical potential depending on energy, radius and momentum. The present theory generalizes the older Fermi-gas and local-density approximations to this problem in the sense that we can assess precisely the validity of our approach. We show that it yields results which coincide with the average part of a corresponding quantal calculation. We use a gaussian finite-range effective interaction derived from the Gogny force and phenomenological mean-field potentials of the Woods-Saxon or harmonic-oscillator type. With these ingredients and no further adjustable parameters our results for the depth and volume integrals are in good agreement with the average trend of the elastic scattering data. Further, the resulting momentum dependence of W is strong, especially for small P. The influence of the Pauli principle is studied in detail. 相似文献
5.
M.?BeyerEmail author S.?Strauss P.?Schuck S.?A.?Sofianos 《The European Physical Journal A - Hadrons and Nuclei》2004,22(2):261-269
We investigate properties and the distribution of light nuclei (
) in symmetric nuclear matter of finite temperature within a microscopic framework. For this purpose we have solved few-body Alt-Grassberger-Sandhas-type equations for quasi-nucleons that include self-energy corrections and Pauli blocking in a systematic way. In a statistical model we find a significant influence in the composition of nuclear matter if medium effects are included in the microscopic calculation of nuclei. If multiplicities are frozen out at a certain time (or volume), we expect significant consequences for the formation of light fragments in a heavy ion collision. As a consequence of the systematic inclusion of medium effects, the ordering of multiplicities becomes opposite to the law-of-mass action of ideal components. This is necessary to explain the large abundance of
-particles in a heavy ion collision that are otherwise largely suppressed in an ideal equilibrium scenario.PACS:
25.70.-z Low and intermediate energy heavy-ion reactions - 25.70.Pq Multifragment emission and correlations - 21.65. + f Nuclear matter - 21.45. + v Few-body systems 相似文献
6.
Jacobi BG Laitar DS Pu L Wargocki MF DiPasquale AG Fortner KC Schuck SM Brown SN 《Inorganic chemistry》2002,41(18):4815-4823
Trimesityliridium(III) (mesityl = 2,4,6-trimethylphenyl) reacts with O(2) to form oxotrimesityliridium(V), (mes)(3)Ir=O, in a reaction that is cleanly second order in iridium. In contrast to initial reports by Wilkinson, there is no evidence for substantial accumulation of an intermediate in this reaction. The oxo complex (mes)(3)Ir=O oxidizes triphenylphosphine to triphenylphosphine oxide in a second-order reaction with DeltaH++ = 10.04 +/- 0.16 kcal/mol and DeltaS++ = -21.6 +/- 0.5 cal/(mol.K) in 1,2-dichloroethane. Triphenylarsine is also oxidized, though over an order of magnitude more slowly. Ir(mes)(3) binds PPh(3) reversibly (K(assoc) = 84 +/- 3 M(-1) in toluene at 20 degrees C) to form an unsymmetrical, sawhorse-shaped four-coordinate complex, whose temperature-dependent NMR spectra reveal a variety of dynamic processes. Oxygen atom transfer from (mes)(3)Ir=O and dioxygen activation by (mes)(3)Ir can be combined to allow catalytic aerobic oxidations of triphenylphosphine at room temperature and atmospheric pressure with overall activity (approximately 60 turnovers/h) comparable to the fastest reported catalysts. A kinetic model that uses the rates measured for dioxygen activation, atom transfer, and phosphine binding describes the observed catalytic behavior well. Oxotrimesityliridium does not react with sulfides, sulfoxides, alcohols, or alkenes, apparently for kinetic reasons. 相似文献
7.
Self-Consistent RPA is extended in a way so that it is compatible with a variational ansatz for the ground-state wave function
as a fermionic many-body vacuum. Employing the usual equation-of-motion technique, we arrive at extended RPA equations of
the Self-Consistent RPA structure. In principle the Pauli principle is, therefore, fully respected. However, the correlation
functions entering the RPA matrix can only be obtained from a systematic expansion in powers of some combinations of RPA amplitudes.
We demonstrate for a model case that this expansion may converge rapidly. 相似文献
8.
9.
Y. Funaki A. Tohsaki H. Horiuchi P. Schuck G. Röpke 《The European Physical Journal A - Hadrons and Nuclei》2006,28(3):259-263
In order to discuss the spatial extention of the 02
+-state of 12C (Hoyle state), we analyze the inelastic form factor of electron scattering to the Hoyle state, which our 3α-condensate wave
function reproduces very well like previous 3α RGM/GCM models. The analysis is made by varying the size of the Hoyle state
artificially. As a result, we find that only the maximum value of the form factor sensitively depends on its size, while the
positions of maximum and minimum are almost unchanged. This size dependence is found to come from a characteristic feature
of the transition density from the ground state to the Hoyle state. We further show the theoretical predictions of the inelastic
form factor to the 22
+-state of 12C, which was recently observed above the Hoyle state, and of the inelastic form factor to the calculated 03
+-state of 16O, which was conjectured to correspond to the 4α condensed state in previous theoretical work by the present authors. 相似文献
10.
The curvature energy coefficient of the nuclear mass formulaa c is first calculated for the model case of a Fermi gas bounded by an external Woods-Saxon potential. The semiclassical theory of Wigner and Kirkwood is used anda c is found to be close to zero. It is, however, shown that this low value is due to the lack of selfconsistency of the potential. When available, the results of the model compare very well with quantal values and the extrapolation to the spherical cavity (billiard) checks with the value fora c known from the Balian-Bloch theory. Second, the selfconsistent case is generalised to finite range forces. No indication is found that this modifies the fact that all theoretical values for a c are larger than about 7 MeV which is an order of magnitude above the empirical value. 相似文献