1,379 research outputs found
Quantal Two-Centre Coulomb Problem treated by means of the Phase-Integral Method II. Quantization Conditions in the Symmetric Case Expressed in Terms of Complete Elliptic Integrals. Numerical Illustration
The contour integrals, occurring in the arbitrary-order phase-integral
quantization conditions given in a previous paper, are in the first- and
third-order approximations expressed in terms of complete elliptic integrals in
the case that the charges of the Coulomb centres are equal. The evaluation of
the integrals is facilitated by the knowledge of quasiclassical dynamics. The
resulting quantization conditions involving complete elliptic integrals are
solved numerically to obtain the energy eigenvalues and the separation
constants of the and states of the hydrogen molecule ion
for various values of the internuclear distance. The accuracy of the formulas
obtained is illustrated by comparison with available numerically exact results.Comment: 19 pages, RevTeX 4, 4 EPS figures, submitted to J. Math. Phy
Excitation of the electric pygmy dipole resonance by inelastic electron scattering
To complete earlier studies of the properties of the electric pygmy dipole
resonance (PDR) obtained in various nuclear reactions, the excitation of the
1 states in Ce by scattering for momentum transfers
~fm is calculated within the plane-wave and distorted-wave
Born approximations. The excited states of the nucleus are described within the
Quasiparticle Random Phase Approximation (QRPA), but also within the
Quasiparticle-Phonon Model (QPM) by accounting for the coupling to complex
configurations. It is demonstrated that the excitation mechanism of the PDR
states in reactions is predominantly of transversal nature for
scattering angles . Being thus mediated by the
convection and spin nuclear currents, the like the
reaction, may provide additional information to the one obtained from Coulomb-
and hadronic excitations of the PDR in , , and
heavy-ion scattering reactions. The calculations predict that the
cross sections for the strongest individual PDR states are in general about
three orders of magnitude smaller as compared to the one of the lowest
state for the studied kinematics, but that they may become dominant at extreme
backward angles.Comment: Prepared for the special issue of EPJA on the topic "Giant, Pygmy,
Pairing Resonances and related topics" dedicated to the memory of Pier
Francesco Bortigno
Self-consistent approach for the quantum confined Stark effect in shallow quantum wells
A computationally efficient, self-consistent complex scaling approach to
calculating characteristics of excitons in an external electric field in
quantum wells is introduced. The method allows one to extract the resonance
position as well as the field-induced broadening for the exciton resonance. For
the case of strong confinement the trial function is represented in factorized
form. The corresponding coupled self-consistent equations, which include the
effective complex potentials, are obtained. The method is applied to the
shallow quantum well. It is shown that in this case the real part of the
effective exciton potential is insensitive to changes of external electric
field up to the ionization threshold, while the imaginary part has
non-analytical field dependence and small for moderate electric fields. This
allows one to express the exciton quasi-energy at some field through the
renormalized expression for the zero-field bound state.Comment: 13 pages, RevTeX4, 6 figure
Anharmonic properties of double giant dipole resonance
A systematic microscopic study of the anharmonic properties of the double
giant dipole resonance (DGDR) has been carried out, for the first time, for
nuclei with mass number spanning the whole mass table. It is concluded that
the corrections of the energy centroid of the and
components of the DGDR from its harmonic limit are negative, have a value of
the order of few hundred keV and follow an dependence.Comment: 4 pages, 2 figure
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