共查询到20条相似文献,搜索用时 0 毫秒
1.
R. Kh. Gainutdinov M. Kh. Salakhov M. A. Khamadeev 《Bulletin of the Russian Academy of Sciences: Physics》2012,76(12):1301-1305
The influence of a photonic crystal medium on the character of the interaction of electrons with their own radiation field is studied. As was recently shown, this influence changes the electromagnetic mass of the electrons in photonic crystals. This alters atomic energy levels. The dependence of this effect on the optical contrast of photonic crystals is studied. 相似文献
2.
Utilizing Hartree-Fock self-consistent field wave functions, accurate values of the potential energy shift at the nucleus due to atomic electrons have been determined for a large number of atoms. An extensive numerical table of values of the shift,V 0, is given and comparison is made with earlier approximate results obtained from the Thomas-Fermi and Thomas-Fermi-Dirac statistical models and with estimates fromK binding energy data. In the calculation of screening corrections to Fermi functions, the Hartree-Fock results present a considerable improvement over earlier estimates from the aforementioned methods. 相似文献
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New high resolution ultraviolet photoemission energy distributions (EDCs) from copper are found to agree best with the calculations of Williams et al., using the Chodorow potential, if an energy dependent shift is made between the experimental and calculated EDCs. It is argued that this shift is most probably due to an energy dependent self energy as discussed by Lundqvist and others. 相似文献
5.
Energy eigenvalues and matrix elements of various anharmonic oscillators are determined to a high accuracy by applying a method
for determining the eigenvalues and eigenvectors of real symmetric para-p diagonal matrices (described in the preceding paper). Our results for the 2- and 3-dimensional oscillators are new and complement
similar accurate results for the one dimensional oscillators available in the literature. 相似文献
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7.
《Nuclear Physics A》1999,657(1):59-72
We apply the time-dependent variational principle, the nuclear field theory, and the boson expansion method to the Lipkin model to discuss anharmonicities of collective vibrational excitations. It is shown that all of these approaches lead to the same anharmonicity to leading order in the number of particles. Comparison with the exact solution of the Lipkin model shows that these theories reproduce quite well. 相似文献
8.
A mechanism is proposed to explain the double phase transitions found in K2PbCu(NO2)6 and Tl2PbCu(NO2)6. The higher temperature transition is caused by the cooperative Jahn-Teller effect. The lower temperature transition occurs as the fourth order anharmonic interaction restabilizes the lattice against instabilities caused by static distortions in the third order anharmonic interaction. Calculated curves of the order parameter and heat capacity reproduce all the features in the experimental curves. 相似文献
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A new square shaped piezoelectric bimorph structure for energy scavenging purposes has been proposed and simulated. It is derived from theoretical analysis that the output power of the structure is proportional to the value of the resonant frequency. The device working in Lame mode has a much higher resonant frequency of 2.39 MHz than devices working in ordinary bending modes, which is expected to significantly increase the energy output of radioisotope power generators (RPGs). The results of static analysis and dynamic response show that output voltage is linear with the applied load; the output power is quadratic with the applied load. 相似文献
11.
G P Srivastava 《Pramana》1974,3(4):209-217
Using the Ziman scheme of considering a drifting Planck’s distribution, as the eigenvector of the linearized phonon collision
operator, the anharmonic relaxation of phonons is discussed. The earlier arbitrariness in the phonon-phonon coupling parameters
is removed by formulating explicit expressions for different allowed processes in terms of measurable quantities. Low and
high temperature approximations of relaxation rates are also discussed: the results differ from earlier calculations. At low
temperatures superthermal or high frequency phonons, which have temperature-independent and equal N- and U-relaxation rates,
play important roles in thermal conduction in pure insulators.
Presently working as University of Wales Fellow in the Applied Physics Department, UWIST Cathays Park, Cardiff CF1 3NU, U.K. 相似文献
12.
Using a high resolution backscattering instrument the energy shift caused by the Zeeman splitting and the inelasticity of the interaction of neutrons with a neutron magnetic resonance system could be observed. Various applications concerning the realization of a dynamical neutron polarization system, the pumping of neutrons into a certain energy interval and the production and handling of ultra cold neutrons are discussed. 相似文献
13.
Krishna Murti Raju 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,84(3):409-417
Data on elastic constants and associated properties at high temperature for TmTe crystal
are presented and discussed starting from primary physical parameters viz. nearest
neighbour distance and hardness parameter assuming long- and short-range potentials. When
the values of the higher order elastic constants are known for a crystal, many of the
anharmonic properties of the crystal can be treated within the limit of the continuum
approximation in a quantitative manner. In this study, higher order elastic constants and
related properties are computed upto 1000 K for TmTe. The first-order pressure derivatives
of second- and third-order elastic constants, the second-order pressure derivatives of
second-order elastic constants and partial contractions are also evaluated at different
temperatures. The results thus obtained are compared with other available data and found
in well agreement with present values. 相似文献
14.
Intensity-induced mode shift in a femtosecond laser by a change in the nonlinear index of refraction
The modes of the comb spectrum of a Kerr-lens mode-locked laser are frequency shifted versus the corresponding cw modes of the cavity by an intensity-induced change in the index of refraction in the Kerr medium. We demonstrate this effect and discuss novel schemes for fast frequency control of the comb spectrum. 相似文献
15.
Mode shift and stability control of a current mode controlled buck-boost converter operating in discontinuous conduction mode with ramp compensation 下载免费PDF全文
By establishing the discrete iterative mapping model of a
current mode controlled buck-boost converter, this paper studies the
mechanism of mode shift and stability control of the buck-boost
converter operating in discontinuous conduction mode with a ramp
compensation current. With the bifurcation diagram, Lyapunov
exponent spectrum, time-domain waveform and parameter space map, the
performance of the buck-boost converter circuit utilizing a
compensating ramp current has been analysed. The obtained results
indicate that the system trajectory is weakly chaotic and strongly
intermittent under discontinuous conduction mode. By using ramp
compensation, the buck-boost converter can shift from discontinuous
conduction mode to continuous conduction mode, and effectively
operates in the stable period-one region. 相似文献
16.
Passive cw mode locking of an ytterbium-doped fluoride phosphate glass laser is demonstrated, for what we believe to be the first time, based solely on the Kerr effect in the active medium in a resonator with dispersion compensation. Nearly bandwidth-limited pulses as short as 160fs are generated at ~1040 nm. We obtain average output powers as high as 250mW at 170-MHz repetition rate with absorbed pump power as low as 1.2W. 相似文献
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18.
L. Holz M. Pfeiffer H. Gaber A. Lau 《Applied Physics A: Materials Science & Processing》1995,61(2):171-175
Fullerence C60 exhibits a continuous and reversibleA
g
(2) mode softening from 1469 to 1459 cm–1, which is linear with laser power up to 21.9 kW/cm2 for C60 crystals under vacuum. Model calculations taking into account the temperature distribution that is induced by the Gaussian intensity profile of the laser beam reproduce the measured frequency shifts. A thermal conductivity of microcrystalline fullerene of 0.27(±0.03) W/mK is derived from this numerical analysis. 相似文献
19.
A diffractive slab structure comprising a mirror, a dielectric film, and a grating in the film is made to always exhibit 100% diffraction efficiency for the – 1st order pointing in a backward direction. The design is obtained by sole interference reasoning, and confirmed numerically. 相似文献
20.
We recalculate the two loop corrections in the background heat bath using real time formalism. The procedure of the integrations of loop momenta with dependence on finite temperature before the momenta without it has been followed. We determine the mass and wavefunction renormalization constants in the low temperature limit of QED, for the first time with this preferred order of integrations. The correction to electron mass and spinors in this limit is important in the early universe at the time of primordial nucleosynthesis as well as in astrophysics. 相似文献