The equations of motion of the Hénon-Heiles model have been numerically integrated for 100 different starting conditions on the critical energy surface E=1/6. The truncation error in the data was monitored using ...
The equations of motion of the Hénon-Heiles model have been numerically integrated for 100 different starting conditions on the critical energy surface E=1/6. The truncation error in the data was monitored using the separation in phase space of two numerical histories with the same initial conditions, based on different time steps, h=2−13 and h’=2−14. From the data for which the truncation error is less than 1% it is found that the 100 histories fall into three categories, (a) regular (or quasiperiodic), (b) irregular (or chaotic), and (c) regular-irregular. The three-dimensional phase space portraits prove to be the most useful tool in distinguishing between regular and irregular behavior. In category (c) the orbit switches reversibly from (to) regular to (from) irregular behavior. The data suggest that all 100 orbits, followed for long enough times, will show regular-irregular behavior and moreover the phase points in these orbits will spend, on average, equal amounts of time in the quasiperiodic and chaotic regimes.
Samples of solid deuterium, cooled below 4.2 K, and irradiated by 15 MeV protons, will spontaneously flash. The flash-spectrum occurs in the near infrared with a maximum close to 920 nm. The flash intensity is two to ...
Samples of solid deuterium, cooled below 4.2 K, and irradiated by 15 MeV protons, will spontaneously flash. The flash-spectrum occurs in the near infrared with a maximum close to 920 nm. The flash intensity is two to three orders of magnitude greater than a steady-state emission observed in the same spectral region. The flash frequency is 1 every 1 to 3 min after several hours of irradiation of 10 nA/cm2. Heat pulses have been detected accompanying many of the flashes and both can be stimulated by the application of external heat triggers. Following the optical flash, the steady-state emission intensity decreases by an amount that is wavelength dependent. While it is thought that these flashes are caused by atomic association in the solid, the species responsible for the optical emission is uncertain as is the transition itself.
Methods of standardization in quantitative micro-PIXE analysis are reviewed and various issues that bear on analytical accuracy are explored;pertinent recent work on Si(Li) X-ray detector response is included and some...
Methods of standardization in quantitative micro-PIXE analysis are reviewed and various issues that bear on analytical accuracy are explored;pertinent recent work on Si(Li) X-ray detector response is included and some geochemical examples are drawn upon. Extension of the GUPIX software to deal with multilayer targets, including secondary fluorescence within and between layers, is reported;analytical examples include alloy foils and multilayer solar cell structures.
Effect of J term in the t-t'-J model on the Fermi surface, density of states and the Drude plasma frequency have been studied. The J term is treated within the uniform bond theory of Affleck and Marston [Phys. Rev...
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Effect of J term in the t-t'-J model on the Fermi surface, density of states and the Drude plasma frequency have been studied. The J term is treated within the uniform bond theory of Affleck and Marston [Phys. Rev. B39, 11538 (1989)]. Inclusion of the J term succeeds in removing the Brinkman-Rice divergence in the density of states at Fermi energy but fails to obtain an insulating state at zero doping. We have also shown that an exact treatment of the J term does indeed lead to an insulating' state at half-filling.
Trace element analysis of mineral grains by micro-PIXE demands prior knowledge of major element concentrations from which the appropriate matrix corrections are derived. We describe the micro-PIXE determination of maj...
Trace element analysis of mineral grains by micro-PIXE demands prior knowledge of major element concentrations from which the appropriate matrix corrections are derived. We describe the micro-PIXE determination of major elements using 750 keV protons. The major element concentrations measured for a variety of minerals are in good agreement with recommended values.
The inelastic depolarized light-scattering spectrum of the endohedral metallofullerene Li+ @ C60 is calculated for frequency shifts up to 1000 cm-1. In this species the motion of the charged inclusion within the bucky...
The inelastic depolarized light-scattering spectrum of the endohedral metallofullerene Li+ @ C60 is calculated for frequency shifts up to 1000 cm-1. In this species the motion of the charged inclusion within the buckyball cage generates an induced anisotropic polarizability through an interesting mechanism involving the hyperpolarizability B. The resulting Raman spectrum is quite intense. At room temperature, hot bands contribute significantly to the scattering.
The infrared spectrum of the endohedral metallofullerene Li+ @ C60 is calculated. Vibrational and rotational motion of the charged inclusion leads to the emission and absorption of radiation. Our calculations assume t...
The infrared spectrum of the endohedral metallofullerene Li+ @ C60 is calculated. Vibrational and rotational motion of the charged inclusion leads to the emission and absorption of radiation. Our calculations assume this motion is governed by the intramolecular ''reflected Morse'' potential of Dunlap, Ballester and Schmidt. The predicted pure rotation band peaks near 40 cm-1. The fundamental vibration-rotation band at 350 cm-1 exhibits unusual band-head structure. Both bands are intense. The first overtone band at 700 cm-1 is also studied. Rotational structure is well resolved in all three bands;at room temperature, hot bands contribute significantly.
We compute the far-infrared absorption spectrum of the endohedral metallofullerene K+ @ C60. This arises from the vibrational and rotational motion of the potassium ion about its equilibrium position at the center of ...
We compute the far-infrared absorption spectrum of the endohedral metallofullerene K+ @ C60. This arises from the vibrational and rotational motion of the potassium ion about its equilibrium position at the center of the buckyball cage. The spectrum is quite unusual. Although the permanent dipole moment of the complex is zero, absorption is very intense. The spectrum contains a pure rotation band, which peaks near 55 cm-1 at 25-degrees-C. There is also a fundamental vibration-rotation band, consisting of a strong P-branch at 70 cm-1, overlapping the rotational band, and a much weaker R-branch at 180 cm-1. Line-spacing is strongly dependent on the rotational quantum number. Hot bands contribute significantly to the intensity. We include a discussion of dipolar shielding effects.
Making use of the Poisson summation formula in m dimensions, a class of phase-modulated lattice sums is evaluated analytically. The resulting formulas provide a broad generalization of the results reported previously ...
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Making use of the Poisson summation formula in m dimensions, a class of phase-modulated lattice sums is evaluated analytically. The resulting formulas provide a broad generalization of the results reported previously and are of considerable use in the analysis of finite-size effects in systems undergoing phase transitions, especially when the boundary conditions imposed are other than periodic.
Scanning micro-PIXE is employed in conjunction with backscatter electron imaging and cathodoluminescence to study oscillatory zoning of minor and trace elements in natural and synthetic minerals. The scanning proton m...
Scanning micro-PIXE is employed in conjunction with backscatter electron imaging and cathodoluminescence to study oscillatory zoning of minor and trace elements in natural and synthetic minerals. The scanning proton microprobe (SPM) is also used to study surface features on individual mineral grains.
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