Self-consistent Effective Interactions Research Articles

Description of collective states in Os192 within the boson expansion theory

The low-lying collective states in $^{192}\mathrm{Os}$ are investigated microscopically by means of the boson expansion theory with the self-consistent effective interactions. The building blocks of the collective boson, the collective potential, and the structures of the wave functions for some relevant states are illustrated. Calculated level energies and electromagnetic properties are compared with the experimental data. Properties of some low-lying states and relevant quasibands are discussed with the help of the boson description of state vectors.

Description of low-lying collective states in osmium isotopes in the boson expansion theory

The low-lying collective states in osmium isotopes are investigated microscopically by means of the boson expansion theory with the self-consistent effective interactions. The potential energy surfaces and the structures of boson wave functions are illustrated. Theoretical level structures and electromagnetic properties are compared with the available experimental data. The prolate-oblate shape transition predicted at around N = 116 is also discussed in terms of the evolution of the theoretical potential as the neutron number changes.

Boson description of low-lying collective states inBa128

The low-lying collective states in $^{128}\mathrm{Ba}$ are investigated microscopically by means of the boson expansion theory with the self-consistent effective interactions. Calculated level structures and electromagnetic properties are compared with the experimental data. Theoretical structures of the collective wave functions are illustrated in detail for ${0}_{1}^{+},\phantom{\rule{0.16em}{0ex}}{0}_{2}^{+},\phantom{\rule{0.16em}{0ex}}{0}_{3}^{+},\phantom{\rule{0.16em}{0ex}}{2}_{1}^{+},\phantom{\rule{0.16em}{0ex}}{2}_{2}^{+}$, and ${2}_{3}^{+}$ states. In the present results, the main contribution to the ${0}_{2}^{+}$ state of $^{128}\mathrm{Ba}$ comes from the three-phonon component, and the two-phonon component is rather dominant in the ${0}_{3}^{+}$ state. The description of the wave functions is compared to the results of the general collective model.

COMPETING MINIMA AND NON-AXIAL SADDLES IN SUPERHEAVY NUCLEI

Energy landscapes of superheavy even-even nuclei with 116 ≤ Z ≤ 126 and 176 ≤ N ≤ 184 are studied within the macroscopic-microscopic method over a 12 dimensional manifold of shapes, including both axial- and mass-asymmetry. In addition to the spherical, prolate and oblate minima we find also oblate-octupole minima, with Y33 symmetry along the oblateness axis, that compete to become ground states. All fission saddle points are triaxial and by 0.5-2.5 MeV lower than the axial ones. The Woods-Saxon model predicts the abrupt lowering of barriers near Z = 126, in a stark contrast to the mostly used self-consistent effective interactions.

Self-consistent effective interactions in charged colloidal suspensions

We use an integral equation scheme to obtain self-consistently the effective interaction between colloids in salt-free charged colloidal suspensions. The colloid–counterion direct correlation function (DCF) is obtained for the fixed colloid–colloid pair structure by solving the corresponding hypernetted-chain equation (HNC). This DCF is then used to formulate an effective colloid–colloid pair potential for which the one-component reference hypernetted-chain equation is solved. Both processes are iterated until self-consistency is achieved. Counterion–counterion correlations are considered linear and uncoupled from the rest of the correlations. The method is based on a similar treatment utilized in liquid metals [Phys. Rev. B 61, 11400 (2000)] and provides equivalent results to those obtained using the standard multicomponent HNC equation for mixtures of charged hard spheres. The theory proves rather accurate when compared with molecular dynamic simulations of charged hard and soft spheres for colloidal charges of up to 300. We study in detail the existence of net attractions between colloids in certain cases (especially in the presence of divalent and trivalent counterions) and how this attraction may lead to phase instability. The problem of the lack of solution of the integral equation for more realistic cases (larger charges) is also discussed.

Selfconsistent effective interactions and symmetry restoration

The present paper clarifies on the quantum level the concept of selfconsistent interactions and symmetry restoration by means of the generalized scaling fields. It is shown that the concept of symmetry restoration in RPA order can directly be related to the concept of selfconsistent interations. The difference of the two methods originates from the coupling of the kinetic energy operator to the perturbing field. The presented method is superior to the semiclassical approach. It also yields, in its limiting case, the multipole-multipole effective interaction.

Self-consistent velocity dependent effective interactions.

The theory of self-consistent effective interactions in nuclei is extended for a system with a velocity dependent mean potential. By means of the field coupling method, we present a general prescription to derive effective interactions which are consistent with the mean potential. For a deformed system with the conventional pairing field, the velocity dependent effective interactions are derived as the multipole pairing interactions in doubly stretched coordinates. They are applied to the microscopic analysis of the giant dipole resonances (GDR's) of $^{148,154}\mathrm{Sm}$, the first excited ${2}^{+}$ states of Sn isotopes and the first excited ${3}^{\mathrm{\ensuremath{-}}}$ states of Mo isotopes. It is clarified that the interactions play crucial roles in describing the splitting and structure of GDR peaks, in restoring the energy weighted sum rule, and in reducing the values of B(E\ensuremath{\lambda}). \textcopyright{} 1996 The American Physical Society.

Translational symmetry of a nuclear hamiltonian and the improved multipole interaction model

A theory of self-consistent effective interactions in nuclei, developed in our previous work, is applied further to a two-component system with \\̊gwn ≠ \\̊gwp on the basis of an oscillator model. As a result, an improved form of the multipole interaction is proposed. It is shown that the translational invariance of a nuclear hamiltonian is guaranteed in this model. Decoupling of a dipole mode from an octupole mode in a deformed system is also discussed.

Microscopic analysis of nuclear collective motions in terms of the boson expansion theory: (II). Numerical calculations

Anharmonicities in nuclear quadrupole collective motions are studied by applying the self-consistent effective interactions derived in our previous work. Numerical calculations are made in terms of the boson expansion technique of Kishimoto-Tamura with several new refinements developed in the first paper of this series. It is shown that the three-body interaction is necessary to maintain the integrity of the collective modes in the presence of coupling with quasi-particle modes. General agreements with experimental data on nuclei in various mass region have confirmed that our theory is capable of describing various types of anharmonicities characteristic to the nuclei in question.

Origin of the multipole pairing interactions

The self-consistent effective interactions in nuclei under the influence of the monopole pairing correlation are investigated. It is shown that the multipole pairing interactions are induced so as to restore the local galilean invariance of the system.

Self-consistent effective interactions in nuclei: (I). Doubly-stretched multipole interactions in deformed nuclei

The self-consistent effective interactions in nuclei are studied in detail by putting strong emphasis on the concept of nuclear saturation and the self-consistency between the shape of an average potential and that of a density distribution (nuclear self-consistency). The conventional multipole interaction model is improved so as to satisfy the nuclear self-consistency rigorously even if the system is deformed. The resulting doubly-stretched multipole interaction model is then examined by applying to low-lying collective states and high-frequency giant resonances in deformed nuclei.

Self-consistent effective interactions in nuclei: (II). Higher-order effective interactions in nuclei

This paper attempts to develop a general theory of self-consistent effective interactions in nuclei which are reliable for describing the anharmonicities in nuclear collective motions caused by couplings between various modes of motion. Based on the concept of nuclear saturation and the self-consistency between the shape of an average potential and that of a density distribution (nuclear self-consistency), higher-order effective interactions (e.g. a three-body interaction, etc.) are derived in order to satisfy the nuclear self-consistency in higher-order accuracy when more than one mode is simultaneously excited in the system. The physical meaning of the interactions thus derived and the effect of them on the mode-mode couplings are discussed.

Microscopic and macroscopic calculations of the breathing mode state

The energy of the breathing mode in nuclei can be calculated both from a macroscopic point of view via the nuclear compressibility and from a microscopic point of view in the TDA and RPA formalisms. We compare results of both types of calculation for 16O using several self-consistent effective interactions and a couple of more traditional interactions motivated by nuclear structure. We comment on the degree of consistency between the results of both types of calculation, some of the technical considerations in carrying out the calculations, and some of the extremes to which the effective interaction can be pushed without changing the breathing mode energy.