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Showing papers on "Random phase approximation published in 1980"


Journal ArticleDOI
TL;DR: In this article, a microscopic particle-vibration model is used to study the single-particle energies, spectroscopic factors and nucleon effective mass in 208 Pb. The relevant quantities are deduced from the knowledge of the mass operator which is the sum of a Hartree-Fock term and an energy dependent term coming from the coupling to RPA vibrations.

133 citations


Journal ArticleDOI
TL;DR: The relativistic random phase approximation (RRPA) as discussed by the authors was developed from linearized time-dependent Hartree-Fock theory and applied to determine excitation energies and oscillator strengths along the He, Be, Mg, Zn and Ne isoelectronic sequences.
Abstract: The relativistic random phase approximation RRPA is developed from linearized time-dependent Hartree-Fock theory. Applications of the resulting relativistic many-body equations to determine excitation energies and oscillator strengths along the He, Be, Mg, Zn and Ne isoelectronic sequences are discussed and compared with other recent experimental and theoretical work. The multi-channel RRPA treatment of photoionization is described and applications are given to total cross sections, branching ratios, angular distributions and to autoionizing resonances.

111 citations


Journal ArticleDOI
TL;DR: In this paper, the electric field acting on an oscillating dipole located near a metal surface is computed by a jellium model and the random phase approximation, and the aim is to ascertain to what extent spatial dispersion and variation of the dielectric properties across the interface modify the image dipole.

55 citations


Journal ArticleDOI
TL;DR: In this paper, a functional integral representation for the many-body time evolution operator was proposed for a microscopic description of nuclear dynamical problems, and a mean-field approximation for matrix elements of the matrix elements was derived from exact functional integral.
Abstract: A general method for a microscopic description of nuclear dynamical problems is discussed. The method is based on a functional integral representation for the many-body time evolution operator $U({t}_{f},{t}_{i})$. In the stationary phase limit, a time-dependent mean-field approximation for the matrix elements of $U$ is obtained. Using standard procedures this allows for extraction of quantum mechanical information about bound states, tunneling, or scattering phenomena in a many-nucleon system. The approximation represents a natural generalization of the time-dependent Hartree-Fock method.NUCLEAR STRUCTURE, NUCLEAR REACTIONS derived mean-field approximation for matrix elements of $\mathrm{exp}(\ensuremath{-}iHt)$ from exact functional integral; discussed relation to static HF, TDHF, and scattering calculations.

49 citations


Journal ArticleDOI
TL;DR: In this paper, the experimental data were analyzed in the distorted-wave Born approximation (DWBA) with wave functions calculated in the random phase approximation (RPA), and three J π = 1 + states have been identified E x = 8.233, 9.000 and 9.371 MeV.

42 citations


Journal ArticleDOI
TL;DR: In this paper, the interaction between the molecular charge density and the free electrons in the metal is treated within the random phase approximation, and applications to infrared, electron energy loss and Raman spectroscopy, as well as to the computation of dispersion forces between chemisorbed molecules are discussed.
Abstract: It is known that the spectroscopic properties of a chemisorbed molecule are affected by the interaction between the molecular charge density and the free electrons in the metal. Such effects have been previously discussed by using a model in which the molecule is represented by a point dipole and its interaction with the metal is treated by using macroscopic electrodynamics. We examine critically this model and remove some of its shortcomings by developing a microscopic theory in which the interaction between the molecule and the metal is treated within the random phase approximation. We discuss applications to infrared, electron energy loss and Raman spectroscopy, as well as to the computation of dispersion forces between chemisorbed molecules.

41 citations


Journal ArticleDOI
TL;DR: In this article, the random phase approximation (RPA) was used to investigate ground-state correlations in the yrast wave functions of realistic nuclei at high spins, which can be taken into account in a theory with uncorrelated product states by a simple renormalization of the effective interaction.

33 citations


Journal ArticleDOI
TL;DR: It is shown that, while RPA restores symmetry in some respects, it does not do so completely, and the generalisation of RPA that describes modes in isobars of the given nucleus is discussed.

30 citations


Journal ArticleDOI
TL;DR: In this article, the dielectric response of a two dimensional electron gas under a strong transverse magnetic field is obtained within a selfconsistent procedure in which the broadening of Landau levels due to collisional damping from the impurities both determines and is determined by the static dielectrics function of the system.

27 citations


Journal ArticleDOI
TL;DR: The combined time-dependent Hartree-Fock cranking description of high-spin rotational motion is investigated in this article, which is shown to be a semiclassical limiting case of the generalized density matrix approach for the study of non-uniform three-dimensional rotation.

26 citations



Journal ArticleDOI
15 Oct 1980
TL;DR: Inelastic scattering of fast electron from the electronic ground state of the H 2 molecule has been investigated within the first Born approximation as discussed by the authors, and the relevant transition properties have been obtained in some approximation corresponding so-called so-??? order solutions of the equations-of-motion formation put forward by Rowe-Tamm-???approximation, random phase approximation.
Abstract: Inelastic scattering of fast electron from the electronic ground state of the H 2 molecule is investigated within the first Born approximation. The relevant transition properties have been obtained in some approximation corresponding so ??? order solutions of the equations-of-motion formation put forward by Rowe-Tamm-???approximation, random phase approximation. Generalized oscillator strengths and ??? of different symmetry are evaluated and discussed.

Journal ArticleDOI
TL;DR: In this paper, the consistency of the random phase approximation and its generalizations are reviewed and a special attention is given to the ground state correlation energy problem as reflected in the calculation of chemical bond energies.
Abstract: Recent results concerning the consistency of the random phase approximation and its generalizations are reviewed. Particular attention is given to the ground state correlation energy problem as reflected in the calculation of chemical bond energies.

Journal ArticleDOI
TL;DR: In this paper, a microscopic theory for the isothermal compressibility, the partial volumes, and the stability of liquid alloys with semiconducting behavior at certain stoichiometric compositions is presented in terms of the low-wavenumber limit of the partial structure factors.
Abstract: A microscopic theory for the isothermal compressibility, the partial volumes, and the stability of liquid alloys with semiconducting behaviour at certain stoichiometric compositions is presented in terms of the low wavenumber limit of the partial structure factors. Using the random phase approximation for the Ornstein Zernike direct correlation functions the quantities can be shown to be composed of a hard core part and a part coming from the long range interatomic potentials. The latter are assumed to be composed of a metallic part treated by pseudopotential theory plus an electronically screened attractive Coulomb interaction due to charge transfer. Under the additional assumption of a reduced electronic density of states near the stoichiometric composition the measured anomalies can be qualitatively explained. In the case of LiPb good agreement with experiment is achieved.

Journal ArticleDOI
TL;DR: In this article, the binding energies of electrons trapped in the oscillatory wake of electron density fluctuations trailing a fast ion in a solid have been evaluated within random-phase approximation linear-response theory.
Abstract: The binding energies of electrons trapped in the oscillatory wake of electron-density fluctuations trailing a fast ion in a solid have been evaluated within random-phase approximation linear-response theory. The results are found to be consistent with earlier calculations.

Journal ArticleDOI
TL;DR: In this article, resistivities and Hall coefficients of heavily doped semiconductors in the metallic concentration range were investigated by the degenerate electron gas model with impurity scattering, and the shapes of the screened impurity potentials and the scattering of electrons by them were investigated in detail by the nonlinear Hartree approximation, the Kohn-Sham density functional formalism and the random phase approximation with valley multiplicity.
Abstract: Resistivities and Hall coefficients of heavily doped semiconductors in the metallic concentration range, especially of Sb-doped Ge and P-doped Si, are investigated by the degenerate electron gas model with impurity scattering. The maxima of resistivity and Hall coefficient are explained by strong temperature variation of the screening length, which is due to the smallness of the Fermi temperature T F in the present systems ( T F ∼100 K). The shapes of the screened impurity potentials and the scattering of electrons by them are investigated in detail by the nonlinear Hartree approximation, the Kohn-Sham density functional formalism and the random phase approximation with valley multiplicity. Including nonlinearity of screening and many-body effect, we obtain the values of resistivity which agree very well with experiments for the higher concentration samples of the metallic range.

Journal ArticleDOI
TL;DR: In this article, the authors considered the local field corrections (which are disregarded in the random phase approximation) to the self consistent field, and evaluated these corrections exactly in the framework of the adopted approximation scheme because all the integrals which appear in the expressions can be evaluated analytically.
Abstract: Many-body perturbation theory is developed within the dielectric function method presented in a preceding paper [15]. We have explicitly considered the local field corrections (which are disregarded in the random phase approximation) to the self consistent field. These corrections are of second order in the density-density correlation function x and are evaluated exactly in the framework of the adopted approximation scheme because all the integrals which appear in the expressions can be evaluated analytically. Here the method is applied to π electron systems within the zero differential overlap approximation ; explicit calculations of the excitation energies of the benzene molecule using different parametrizations are presented. Comparison is made with results obtained in the RPA and other schemes.

Journal ArticleDOI
TL;DR: In this paper, the linewidth of the van der Pol Oxcillator was calculated in random phase approximation for weak and strong pumping and also in the largen limit for all pumping.
Abstract: The linewidth of then component van der Pol Oxcillator is calculated in random phase approximation. Forn=2 this model describes a single mode laser. This approximation is asymptotically correct for weak and strong pumping and also in the largen limit for all pumping. The result is in good agreement with numerical results forn=2 in the whole range including the threshold. The corresponding vertex renormalized approximation on the other hand yields poor agreement and the wrong asymptotic value in the limit of strong pumping. The reason for this failure is discussed.

Journal ArticleDOI
TL;DR: In this article, photoelectrons ejected from the outer p 1 2 subshells of the rare gases Ar, Kr, and Xe are shown to be totally polarized at certain energies in the vacuum ultraviolet region of the spectrum.

Journal ArticleDOI
TL;DR: In this paper, a procedure for the application of linear response theory and the random phase approximation to an open shell was presented, and applied to Ca isotopes, and the general features of giant multipole resonances were found to vary smoothly with the mass.

Journal ArticleDOI
TL;DR: In this paper, the structure functions of four typical liquids with a single constant modified attractive perturbing potential inside the core were calculated using the optimised cluster expansion in the random phase approximation with a hard sphere potential.

Journal ArticleDOI
TL;DR: The linear optical properties of homogeneous media and heterogeneous media, e.g., interfaces, are calculated in the random phase approximation taking account of the nonlocal effects which are necessarily present when dealing with matter on such a small scale of distances as discussed by the authors.

Journal ArticleDOI
TL;DR: In this article, the wave functions associated with the pair addition and pair removal modes were calculated by diagonalizing monopole and multipole pairing forces in the Tamm-Dancoff and in the random phase approximation.

Journal ArticleDOI
TL;DR: In this paper, the effects of the electron-hole correlation on the gas-liquid type phase transition and sound attenuation of a system in a strong magnetic field were investigated in a generalized random phase approximation.
Abstract: The effects of the electron-hole correlation on the gas-liquid type phase transition and sound attenuation of electron-hole system in a strong magnetic field are investigated in a generalized random phase approximation. It is shown that the effects of the correlation amount to changing the effective interaction constant in a previous theory [D. Yoshioka: J. Phys. Soc. Jpn. 44 (1978) 363]. Similar calculation of sound attenuation by Kuramoto [Z. Phys. B 35 (1979) 233] is criticized to be inconsistent in the treatment of the Coulomb interaction.

Journal ArticleDOI
TL;DR: In this paper, the many-body perturbation theory is reformulated within the dielectric function method presented in the preceding paper, and the self-energy effects are explicitly considered.
Abstract: The many-body perturbation theory is reformulated within the dielectric function method presented in the preceding paper [12]. The self-energy effects are explicitly considered. These corrections turn out to be important and are calculated to the same level of approximation as the corresponding local-field terms. The method is at the moment applicable to π-electron systems within the zero differential overlap approximation. Explicit calculations of the excitation energies for the benzene molecule, using different parametrizations, are presented. Comparison is made with the results obtained in the random phase approximation (RPA) and other schemes.

Journal ArticleDOI
TL;DR: In this paper, a two-sublattice X-Y antiferromagnet is treated using the second-order Green function theory, and the higher order Green functions are decoupled by the random phase approximation (RPA), and the transition temperature T N, where the paramagnetic staggered susceptibility diverges.

Journal ArticleDOI
TL;DR: In this paper, a graphical procedure is presented for calculating first order transition matrices for a general (open-shell) atom, which can be used to calculate matrix elements of a general one-body operator of rank λ in orbital space and σ in spin space.
Abstract: A graphical procedure is presented for calculating first order transition matrices for a general (open-shell) atom. The first order transition matrix may be used to calculate matrix elements of a general one-body operator of rank λ in orbital space and σ in spin space. In the random phase approximation we obtain a set of N + N' coupled differential equations for N final state radial functions and N' initial state radial functions which completely determine the first order transition matrix for an atomic system having N final state channels. (The relation of N' to N is dependent on the atomic system studied.) These N + N' differential equations reduce to familiar forms in the following cases: (1) When initial state correlations are ignored, we obtain the N coupled differential equations of the Close-Coupling Approximation; (2) When the atom has only closed subshells we obtain N' = N and the 2N coupled differential equations are those obtained in the Chang-Fano version of the Random Phase Approximation.


Journal ArticleDOI
TL;DR: In this article, the rigorous formula of Suzuki for correlation function of classical systems and Ising model is generalized and applied to the rotationally invariant Maier-Saupe Hamiltonian of liquid crystals.
Abstract: The rigorous formula of Suzuki for correlation function of classical systems and Ising model is generalized and applied to the rotationally invariant Maier-Saupe Hamil-tonian of liquid crystals.The results show that the microscopic treatment of the correlation function and magnetic Cotton-Mouton coefficient by one of the authors is indeed correct within the approximation stated. The random phase approximation results of Vertogen and van der Meer is improved. A scheme to describe the thermodynamics of liquid crystals beyond the mean field approximation is proposed.