1,482 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
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
Computer modeling of structure and calculation of the short-range order parameters disordered two-layers AB graphene
Optical models of the molecular atmosphere
The use of optical and laser methods for performing atmospheric investigations has stimulated the development of the optical models of the atmosphere. The principles of constructing the optical models of molecular atmosphere for radiation with different spectral composition (wideband, narrowband, and monochromatic) are considered in the case of linear and nonlinear absorptions. The example of the development of a system which provides for the modeling of the processes of optical-wave energy transfer in the atmosphere is presented. Its physical foundations, structure, programming software, and functioning were considered
Search for weak M1 transitions in Ca with inelastic proton scattering
The spinflip M1 resonance in the doubly magic nucleus Ca, dominated by
a single transition, serves as a reference case for the quenching of
spin-isospin modes in nuclei. The aim of the present work is a search for weak
M1 transitions in Ca with a high-resolution (p,p') experiment at 295 MeV
and forward angles including 0 degree and a comparison to results from a
similar study using backward-angle electron scattering at low momentum
transfers in order to estimate their contribution to the total B(M1) strength.
M1 cross sections of individual peaks in the spectra are deduced with a
multipole decomposition analysis. The corresponding reduced B(M1) transition
strengths are extracted following the approach outlined in J. Birkhan et al.,
Phys. Rev. C 93, 041302(R) (2016). In total, 29 peaks containing a M1
contribution are found in the excitation energy region 7 - 13 MeV. The
resulting B(M1) strength distribution compares well to the electron scattering
results considering different factors limiting the sensitivity in both
experiments and the enhanced importance of mechanisms breaking the
proportionality of nuclear cross sections and electromagnetic matrix elements
for weak transitions as studied here. The total strength of 1.19(6)
deduced assuming a non-quenched isoscalar part of the (p,p') cross sections
agrees with the (e,e') result of 1.21(13) . A binwise analysis above
10 MeV provides an upper limit of 1.62(23) . The present results
confirm that weak transitions contribute about 25% to the total B(M1) strength
in Ca and the quenching factors of GT and spin-M1 strength are
comparable in fp-shell nuclei. Thus, the role of of meson exchange currents
seems to be neglible, in contrast to sd-shell nuclei.Comment: 11 pages, 9 figures, revised analysis with oxygen contamination
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Role of Russia in peaceful settlement of the conflict of North and South Korea: event analysis
This study analyzes the conflict between North Korea and South Korea. The Russian Federation has played an important role in the peaceful settlement of this conflict, which has an impact on the formation of the appearance of Russia in the international arena. The theoretical basis of the study was the theory of images, communication and international conflicts. Using the eventanalysis method, an event-based picture of the conflict was built, comparative assessments were made, conflicting parties, indirect participants and intermediaries were identified. An analysis of the current situation is given, groups of interests and the role of Russia in the peaceful settlement of this conflict are identified.Este estudio analiza el conflicto entre Corea del Norte y Corea del Sur. La Federación de Rusia ha desempeñado un papel importante en la solución pacífica de este conflicto, que tiene un impacto en la formación de la aparición de Rusia en la arena internacional. La base teórica del estudio fue la teoría de las imágenes, la comunicación y los conflictos internacionales. Utilizando el método de análisis de eventos, se construyó una imagen del conflicto basada en eventos, se realizaron evaluaciones comparativas, se identificaron las partes en conflicto, los participantes indirectos y los intermediarios. Se presenta un análisis de la situación actual, se identifican los grupos de intereses y el papel de Rusia en la solución pacífica de este conflicto.Este estudo analisa o conflito entre a Coréia do Norte e a Coréia do Sul. A Federação Russa tem desempenhado um papel importante na solução pacífica deste conflito, que tem um impacto sobre a formação da aparição da Rússia na arena internacional. A base teórica do estudo foi a teoria das imagens, comunicação e conflitos internacionais. Usando o método de análise de eventos, uma imagem baseada em eventos do conflito foi construída, avaliações comparativas foram feitas, partes conflitantes, participantes indiretos e intermediários foram identificados. Uma análise da situação atual é dada, grupos de interesses e o papel da Rússia na solução pacífica deste conflito são identificados
Ab-initio study of cation-rich InP(001) and GaP(001) surface reconstructions and iodine adsorption
Atomic and electronic structures for a number of InP and GaP (001) surface geometries were studied within the density functional theory (DFT) in order to reexamine the energy stability of surface reconstructions in the cation-rich limit. It is shown that in both cases the mixed dimer (2×4) reconstruction is the energetically favored in the cation rich limit. The ζ(4×2) reconstruction has the lowest surface energy among considered (4×2) surface structures. Comparative theoretical study of iodine adsorption on the semiconductor surface with ζ(4×2) and mixed dimer (2×4) structures was performed. It was shown that iodine prefers to be bonded with dimerized cation atoms irrespective on the surface reconstruction
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