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1.
Physics of the Solid State - The elastic properties of compressed Ne, Ar, Kr, and Xe rare-gas crystals were studied in a model of deformable and polarizable atoms. The second-order Fuchs elasticity... 相似文献
2.
The lattice dynamics of rare-gas crystals is investigated in the framework of the ab initio approach with the inclusion of the nonadiabatic effects over a wide range of pressures. The frequencies of phonons in argon, krypton, and xenon crystals are calculated at pressures p ≠ 0. Analysis of the contributions from different interactions to the lattice dynamics of the crystals demonstrates that the difference between the phonon frequencies calculated within several models is most pronounced at the boundary of the Brillouin zone. Under strong compressions, the phonon spectrum along the Δ direction is distorted and the longitudinal mode is softened as a result of the electron-phonon interaction, with the relative contribution decreasing in the series Ar, Kr, and Xe. The calculated phonon frequencies are in good agreement with the experimental data available in the literature for argon crystals at a pressure p = 3.1 GPa. 相似文献
3.
E. P. Troitskaya V. V. Chabanenko I. V. Zhikharev Ie. Ie. Gorbenko E. A. Pilipenko 《Physics of the Solid State》2013,55(2):389-395
An ab initio version of the model with deformable atoms has been constructed to investigate the elastic properties of compressed crystalline neon. Approximations for the calculating parameters of quadrupole deformation of atomic electron shells have been discussed. It has been shown that the pressure dependence of the deviation from the Cauchy relation δ is the result of two competitive interactions, namely, the many-body and electron-phonon interactions, which manifests itself in the deformation of atomic electron shells during the shift of nuclei. In the case of Ne, contributions of these interactions are compensated to a large degree, which provides a weakly pressure-dependent positive value for δ. The agreement of calculated elastic moduli and deviations from the Cauchy relation for Ne with the experiment is good. 相似文献
4.
E. P. Troitskaya Val. V. Chabanenko I. V. Zhikharev Ie. Ie. Gorbenko E. A. Pilipenko 《Physics of the Solid State》2012,54(6):1254-1262
The lattice dynamics of rare-gas crystals has been constructed taking into account the deformation of electron shells of the atoms of the dipole and quadrupole types, depending on the displacement of the nuclei. The obtained equations of lattice vibrations have been investigated in the long-wavelength approximation. The role played by the three-body interaction and the deformation of the electron shells in the violation of the Cauchy relation has been discussed. The calculated Birch elastic moduli for Xe and deviations from the Cauchy relation are in good agreement with the available experimental data over a wide range of pressures. 相似文献
5.
采用TLHT势和经典分子动力学方法研究了稀有气体原子(He,Ne,Ar,Kr,Xe)进入带缺陷的单壁纳米碳管(SWCNT)的动力学过程,计算出了稀有气体原子分别从管壁和管口入射时,它们能封装在SWCNT中的能量阈值Ek0,并与理想结构情形做了比较.结果表明:随着管壁缺陷半径r的增加,Ek0减小;当r<4.5 ?时,给定合适的初始动能,稀有气体原子能封装在纳米碳管中;而r=4.5 ?时,稀有气体原子不能封装在碳管中,且此时缺陷对Ar,Kr和Xe的输运特性有很大影响.
关键词:
纳米碳管
缺陷
稀有气体原子
分子动力学模拟 相似文献
6.
Core excitons from 3d levels of Kr and 4d levels of Xe are examined within the integral equation formalism both in the isolated atoms and in the crystals. Earlier interpretation that resonances at the interband edge Kr-3d and Xe-4d are due to 1s, 2p, 3p excitons is well supported by the present calculation. 相似文献
7.
E. P. Troitskaya Val. V. Chabanenko E. E. Horbenko N. V. Kuzovoy 《Physics of the Solid State》2008,50(4):724-732
The lattice dynamics of compressed rare-gas crystals is theoretically investigated within the ab initio approach in the framework of the Tolpygo model, which explicitly includes the deformation of electron shells in the dipole approximation. The phonon frequencies of compressed rare-gas crystals are calculated with allowance made for the electron-phonon interaction at the mean-value points with the use of the dynamic matrix constructed with the ab initio short-range repulsive potential. The energy of zero-point vibrations and the heat capacity of compressed krypton and xenon face-centered cubic crystals are calculated in the harmonic approximation. The calculated temperature dependences of the specific heat capacity and the Debye temperature are in good agreement with the data available in the literature on the experiment at zero pressure and the results of the calculations within the density-functional theory for all pressures. The quantum effects, in particular, the energies E zp of zero-point vibrations for krypton and xenon crystals, are investigated at different pressures. 相似文献
8.
采用TLHT势和经典分子动力学方法研究了稀有气体原子进入单壁纳米碳管(SWCNT)的动力学过程,计算得出SWCNT能吸入稀有气体原子(He,Ne,Ar,Kr,Xe)的管径阈值r0分别为6.3 ?,7.0 ?,8.6 ?,8.6 ?,8.6 ?,同时计算了对应的每种稀有气体原子能封装在不同管径的SWCNT中的最大初始动能Ek0.计算给出有趣的结果是封装在纳米碳管中的稀有气体原子在管中不停地作周期性振荡,振荡周期与原子进入管中的能量无关,振幅与原子进入管中的能量有关,即振幅随着入射能量的增加而增加.分析表明:给定合适类型的碳管,具有很小初始动能的稀有气体原子可在碳管中稳定的周期性振荡,其振荡频率可达GHz. 相似文献
9.
《Molecular physics》2012,110(21-22):2751-2760
Accurate ab initio intermolecular potential energy surfaces (IPES) have been obtained for the first time for the ground electronic state of the C2H2–Kr and C2H2–Xe van der Waals complexes. Extensive tests, including complete basis set and all-electron scalar relativistic results, support their calculation at the CCSD(T) level of theory, using small-core relativistic pseudopotentials for the rare-gas atoms and aug-cc-pVQZ basis sets extended with a set of 3s3p2d1f1g mid-bond functions. All results are corrected for the basis set superposition error. The importance of the scalar relativistic and rare-gas outer-core (n–1)d correlation effects is investigated. The calculated IPES, adjusted to analytical functions, are characterized by global minima corresponding to skew T-shaped geometries, in which the Jacobi vector positioning the rare-gas atom with respect to the center of mass of the C2H2 moiety corresponds to distances of 4.064 and 4.229?Å, and angles of 65.22° and 68.67° for C2H2–Kr and C2H2–Xe, respectively. The interaction energy of both complexes is estimated to be ?151.88 (1.817?kJ?mol?1) and ?182.76?cm?1 (2.186?kJ?mol?1), respectively. The evolution of the topology of the IPES as a function of the rare-gas atom, from He to Xe, is also discussed. 相似文献
10.
R. von Pietrowski K. von Haeften T. Laarmann T. Möller L. Museur A. V. Kanaev 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(2):323-336
The electronic and geometric structure of rare gas clusters doped with
rare-gas atoms Rg = Xe, Kr or Ar is investigated with fluorescence excitation
spectroscopy in the VUV spectral range. Several absorption bands are
observed in the region of the first electronic excitations of the impurity
atoms, which are related to the lowest spin-orbit split atomic 3P1
and 1P1 states. Due to influence of surrounding atoms of the
cluster, the atomic lines are shifted to the blue and broadened
(“electronical cage effect”). From the known interaction potentials and
the measured spectral shifts the coordination of the impurity atom in
ArN, KrN, NeN and HeN could be studied in great detail.
In the interior of KrN and ArN the Xe atoms are located in
substitutional sites with 12 nearest neighbours and internuclear distances
comparable to that of the host matrix. In NeN and HeN the cluster
atoms (18 and 22, respectively) arrange themselves around the Xe impurity
with a bondlength comparable to that of the heteronuclear dimer. The results
confirm that He clusters are liquid while Ne clusters are solid for N≥
300. Smaller Ne clusters exhibit a liquid like behaviour. When doping is
strong, small Rgm-clusters (Rg = Xe, Kr, Ar, m≤10 2) are formed
in the interior sites of the host cluster made of Ne or He. Specific
electronically excited states, assigned to interface excitons are observed.
Their absorption bands appear and shift towards lower energy when the
cluster size m increases, according to the Frenkel exciton model. The
characteristic bulk excitons appear in the spectra, only when the cluster
radius exceeds the penetration depth of the interface exciton, which can be
considerably larger than that in free Rgm clusters. This effect is
sensitive to electron affinities of the guest and the host cluster. 相似文献
11.
《Journal of Electron Spectroscopy and Related Phenomena》2005,143(1):13-19
The lifetime of core two-hole states in atoms is discussed using an atomic many-body theory. The lifetime widths of the two-hole states with the core holes in the Lx (X = l–3) shells of Ar atom are calculated by an ab initio atomic many-body theory (Green's function method using the extended random-phase approximation with exchange (RPAE)). The present theory gives good agreement with experiment. The changes not only in the Coster-Kronig electron kinetic energy but also in the polarization effect on the Coster-Kronig electron by the presence of extra two holes created by decay of the partner hole or by the presence of the partner hole, affects considerably the lifetime width of the two-hole state in Ar atom so that it deviates much from the sum of that of the individual hole. 相似文献
12.
J. Drnoyan V. I. Zhemenik G. V. Mishinsky 《Physics of Particles and Nuclei Letters》2016,13(3):342-345
Yields of Kr and Xe isotopes in photofission of 232Th, 238U, 237Np, 244Pu, 243Am, and 248Cm were tested for isoscaling dependence. Isoscaling for Kr is revealed. For Xe, isoscaling is found to be affected by the STI and STII fission modes governed by the N = 82 and N = 88 neutron shells. The work was performed at the Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research (JINR). 相似文献
13.
Physics of the Solid State - On the basis of ab initio calculations of the phonon frequencies of compressed rare-gas crystals in the model of deformable and polarizable atoms, dynamic instability... 相似文献
14.
K. Eidmann 《Zeitschrift für Physik A Hadrons and Nuclei》1970,238(2):189-194
The electron temperature has been measured in inductively coupled high frequency gas discharges in Ar, Kr and Xe with the aid of Langmuir probes. The measured temperature shows a rather low radial space dependence up to values ofpR ≈ 30 Torr cm (p=gas pressure,R=radius of the discharge vessel). This behaviour is explained on the basis of the local energy balance of the electrons as a consequence of the energy transport by thermal conduction in the electron gas. 相似文献
15.
Physics of the Solid State - A dynamic matrix of rare-gas crystals is constructed within the model of deformable and polarizable atoms based on the nonempirical short-range repulsion potential... 相似文献
16.
A. I. Parkhomenko A. M. Shalagin 《Journal of Experimental and Theoretical Physics》2014,118(2):192-204
The spectral features of the light-induced drift (LID) velocity for rubidium atoms (85Rb and 87Rb) in an argon buffer medium and in binary buffer mixtures of noble gases (Ne + Ar, Ne + Kr, Ne + Xe, He + Ar, He + Kr, and He + Xe) have been investigated theoretically. A strong temperature dependence of the spectral shape of the LID signal for Rb atoms in an Ar atmosphere is predicted in the temperature range 450 K < T < 800 K. It is shown that the anomalous LID of Rb atoms in binary buffer mixtures of noble gases can be observed at almost any temperature (including the room one) depending on the fractions of neon or helium in these mixtures. The results obtained enable a highly accurate testing of the interatomic interaction potentials used to calculate the drift velocity for anomalous LID in LID experiments. 相似文献
17.
Dr. H. Micklitz Prof. Dr. K. Luchner 《Zeitschrift für Physik A Hadrons and Nuclei》1969,227(4):301-310
By the sudden change of nuclear charge the daughter-ion is excited with a propability of some percent (monopole-excitation). When85Kr is trapped in various solids of rare gases, the daughter-ion Rb+ acts as a probe: The spectra of emitted photons contain information about the influence of the surrounding solid on the levels of the excited Rb+. These spectra have been observed in delayed coincidence with the nuclear process (β-decay); direct excitation by charged particles is excluded. The results are closely connected to the behaviour of the decaying atom in free state and solid krypton: There are narrow bands (the daughter-ion occupies a regular lattice site) and blue-shifted (Δ v) broad bands (emission from daughter-ion displaced to interstitial sites by recoil).Δ v is different in the various solids of rare gases and increases from Ar to Xe; this is due to the various polarizabilities and lattice constants. A theoretical estimate fits well the experimental values. Besides, the experimental results show that the excitation-probability for85Kr in Kr is greater than for85Kr in Ar or Xe, which also agrees with theoretical estimates. Furthermore, information about the displacement energies of the Rb+ in the various solids of rare gases are gained from the ratio of intensities of the narrow bands to that of the broad bands, which are compared to displacement energies gained from rare-gas pair potentials. 相似文献
18.
W. Widdra 《Applied Physics A: Materials Science & Processing》2001,72(4):395-404
Angle-resolved photoemission data are dis-cussed for five different Xe adlayers which exhibit electronic structures of different
dimensionalities. Xe adsorption on Ni (110)-(1 × 2)-3Hand the (×) R30° Xe layer on Ru (001) reveal two-dimensional (2D) Xe-derived band structures that are characteristic for hexagonal rare-gas
layers. Different Xe 5p dispersion widths on Ni and on Ru are found due to the difference in the Xe-Xe nearest-neighbor distance.
For three rare-gas systems (two different Xe coverages on hydrogen-modified Pt (110)-(1 × 2)-H and Kr step decoration on a
Pt (997) surface) true one-dimensional (1D) band structures are found. For Xe step adsorption on Pt (997), electronic localized
(0D) behavior is observed due to an enlarged Xe-Xe separation. The qualitative differences of the band structures in the case
of 2D, 1D and 0D rare-gas systems are demonstrated and are explained by the different dimensionalities of the various structures.
Received: 3 August 2000 / Accepted: 4 August 2000 / Published online: 7 March 2001 相似文献
19.
C.E. Brion I.E. McCarthy I.H. Suzuki E. Weigold G.R.J. Williams K.L. Bedford A.B. Kunz R. Weidman 《Journal of Electron Spectroscopy and Related Phenomena》1982,27(2):83-107
Electron binding energy spectra and momentum distributions have been obtained for the valence orbitals of HBr and HI using noncoplanar symmetric electron coincidence spectroscopy at 1200 eV. The weakly bonding inner valence ns orbitals, which have not been observed previously, have their spectroscopic (pole) strength severely split among a number of ion states. For HBr the strength of the “main” inner valence (ns) transition is 0.42±0.03 whereas for HI it is 0.37±0.04, in close agreement with the value observed for the valence s orbitals of the corresponding isoelectronic inert-gas atoms. The spectroscopic strength for the two outermost orbitals is found to be close to unity, in agreement with many-body Green's function calculations. The measured momentum distributions are compared with several spherically averaged MO momentum distributions, as well as (for HBr) with a Green's function calculation of the generalized overlap amplitude (GOA). The GOA momentum distributions are in excellent agreement with the HBr data, both in shape and relative magnitude. Not all of the MO momentum distributions are in reasonable agreement with the data. Comparison is also made with the calculated momentum distributions for Kr, Br, Xe and I. 相似文献
20.
A statistical mechanical model of solid Kr and Xe monolayers on graphite is described. A phase transition in a Kr monolayer is interpreted as a transition from a solid localised in the surface potential wells of the graphite, to an unlocalised solid having a higher density. Comparison with experimental data enables the graphite well depth to be estimated. Explicit calculations are presented for four different interatomic potential models. The density of the unlocalised phase, the isosteric heat, and the gas-solid transition are given as a function of temperature and pressure for both Kr and Xe. It is shown that Xe first condenses into an unlocalised phase, and its ability to undergo a transition into localisation is examined. It is found that this transition is unlikely at p ? 10?3 Torr where volumetric measurements have been made, but may occur at lower pressures. The gas-solid transition data is re-interpreted in terms of a transition to the unlocalised phase. A combination of the solid-solid and gas-solid transition data is shown to be a good test of interatomic potential models. The comparison is made with particular reference to the magnitude of the Sinanoglu-Pitzer potential. 相似文献