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991.
Use of ab initio pseudopotentials for the assignment of boundary conditions of clusters modeling MgO
V. A. Nasluzov G. L. Gutsev V. V. Rivanenkov K. M. Neiman A. G. Anshits 《Journal of Structural Chemistry》1992,33(2):157-161
Conclusions The work reported in this article was aimed at determining the feasibility and desirability of using ab initio core pseudopotential anionic centers and cluster models of ionic crystals of the type of a cluster implanted in a crystal. The results presented herein, from calculations of a number of clusters of magnesium oxide, demonstrate the promise of this approach for compensation of bond rupture effects. In particular, such a model offers a means for a substantial reduction of the artifact-introduced nonequivalence of the partial ionic densities and the effective charges. The comparatively high reliability of the cluster scheme proposed in this work is also supported by results from calculations of the geometric parameters of the crystal.Branch of Institute of Chemical Physics, Russian Academy of Sciences. Institute of Chemistry of Natural Organic Raw Materials, Siberian Branch, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 2, pp. 3–7, March–April, 1992. 相似文献
992.
Reproducibility for successive determinations with a hanging mercury drop electrode is assessed in relation to solution stirring, drop size and back-diffusion to the mercury thread. The effect of experimental parameters such as drop size, deposition time and gallium concentration on the observed stripping current is investigated. The interference of zinc present in a 0.5M NaSCN + 4.2M NaClO(4) supporting electrolyte on the gallium detection limit and calibration plots is described. Formation of an intermetallic compound with a Zn:Ga ratio of 2:3 and its destruction by co-deposition of zinc with Sb are reported. A detection limit of 10(-8)M gallium was obtained in the presence of 10(-5)M Sb(III). 相似文献
993.
994.
R. Bacaud M. Besson D. Brodzki P. Bussière H. Charcosset G. Diega-Mariadassou M. Oberson B. K. Sharma 《Hyperfine Interactions》1989,46(1-4):583-589
Mössbauer Spectroscopy, X-Ray Diffraction and Electron Microscopy were applied to the study of solid residues of coal hydroliquefaction, for which tin-based catalysts were used. In the general case hydroliquefaction runs were performed in the presence of added sulphur and of finely dispersed SnO2 as a catalyst precursor. The only observed tin species were SnO2 and SnS, the former with percentages higher than expected from XRD, due to its large f factor, the latter as a symmetric doublet, which suggests that any asymmetry should be ascribed to small particle sizes rather than to structure. When the S content was only that of coal and the catalyst precursor β-Sn, FeSn2 occurred together with Sn sulfides and oxides, while no β-Sn was detected. The main catalytic role is ascribed to SnS. 相似文献
995.
K. Matsuishi T. Anzaki S. Onari T. Arai 《International Journal of Infrared and Millimeter Waves》1989,10(7):745-750
Far infrared absorption spectra of amorphous (As2S3)1–x(Sb2S3)x system (x=0.00.6) were measured in the wavenumber region 725 cm–1 with Lamellar grating far infrared Fourier Transform Spectrometer, and the spatial fluctuation of charges and its correlation range were estimated with charge fluctuation model. The charge fluctuation of (As2S3)1–x(Sb2S3)x system increases with Sb2S3 concentration x. On the other hand, the correlation length of the charge fluctuation decreases from 7 A to 4.5 A with an increase in x. As a result, it can be found that the medium range order of As2S3 changes drastically with an incease in Sb2S3 concentration x. 相似文献
996.
V. V. Aivazyan I. V. Ajinenko Yu. A. Belokopytov P. C. Bosetti H. B?ttcher F. Botterweck P. V. Chliapnikov F. Crijns A. De Roeck E. A. De Wolf Th. Driever K. Dziunikowska A. Eskreys W. Friebel Z. C. Garutchava V. G. Gavrjusev H. Graessler P. van Hal T. Haupt W. Kittel S. S. Megrabyan F. Meijers A. B. Micha?owska V. I. Nikolaenko L. C. S. Oliveira K. Olkiewicz L. P. Petrovikh E. Riipinen V. M. Ronjin A. M. Rybin H. M. T. Saarikko W. Schmitz L. Scholten R. Schulte O. G. Tchikilev L. A. Tikhonova A. G. Tomaradze V. A. Uvarov F. Verbeure R. Wischnewski A. Wróblewski S. A. Zotkin NA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1989,42(4):533-542
Forward-backward multiplicity correlations in σ+,K + p andpp collisions at 250 GeV/c ( \(\sqrt s \) =22 GeV) are given for all charges and for the different charge combinations. The correlations are found to be caused predominantly by centrally produced particles. It is demonstrated that this result is an agreement with observations at the ISR and the CERNp \(\bar p\) -Collider. The results are compared to expectations from LUND, DPM and FRITIOF Monte Carlo models and a geometrical picture relating correlations in hadron-hadron collisions toe + e ? data in terms of impact parameters is tested. 相似文献
997.
The properties of neutrinos,s-leptons,s-quarks as well as the coloured isosinglet \(\tilde D\) and \(\tilde D^c \) are studied in superstring inspired models. Furthermore the neutrinoless double β-decay process is investigated, including light and heavy majorana neutrinos, as well as the contribution of the exotic Higgs scalars of the theory. From the current experimental limits onov-ββ-decay, useful constraints are imposed on the masses and Yukawa couplings of the theory. 相似文献
998.
K. D. Duch M. Heel H. Kalinowsky F. Kayser E. Klempt B. May O. Schreiber P. Weidenauer M. Ziegler D. Bailey S. Barlag J. M. Butler U. Gastaldi R. Landua C. Sabev W. Dahme F. Feld-Dahme U. Schaefer W. R. Wodrich J. C. Bizot B. Delcourt J. Jeanjean H. Nguyen E. G. Auld D. A. Axen K. L. Erdman B. Howard R. Howard B. L. White S. Ahmad M. Comyn G. M. Marshall G. Beer L. P. Robertson M. Botlo C. Laa H. Vonach C. Amsler M. Doser J. Riedlberger U. Straumann P. Truöl ASTERIX Collaboration 《Zeitschrift fur Physik C Particles and Fields》1989,45(2):223-234
Antiproton-proton annihilation at rest in a gaseous H2 target at NTP into the final state π+ π? K ± π? (K 0) with an undetectedK 0 or \(\bar K^0 \) has been investigated. We observe theE(1420) resonance in the invariant mass spectrum (K 0)miss K ± π? with massM E =1413±8 MeV/c2 and widthГ E =62 ± 16MeV/c2 and find evidence for the production of thef 1(1285). The absolute branching ratio of \(\bar p\) p → π+ π? E 0,E 0 →K 0 L K ± π ? at (61±6)%P wave annihilation is (3.0±0.9)·10?4 of all annihilations. The observed suppression of theE production fromP wave with respect to theS wave together with some simple selection rules suggest that the quantum numbers of theE(1420) areJ pc=0?+ and not I++. 相似文献
999.
E. Matsinos J. Guy E. Simopoulou W. Venus P. Allport M. Berggren M. Calicchio T. Coghen A. M. Cooper-Sarkar O. Erriquez N. Giannakopoulos G. T. Jones P. Marage M. M. Mobayyen D. R. O. Morrison S. O'Neale M. A. Parker J. Sacton R. A. Sansum N. Schmitz G. W. Van Apeldoorn K. Varvell A. Vayaki H. Wachsmuth W. Wittek BEBC WA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1989,44(1):79-87
Backward proton and pion production is studied in ν and \(\bar v\) charged current interactions in neon. The results are compared with other experiments and theory. The complete backward proton data is compatible with protons produced by reinteractions in the nucleus. However in events with only one proton, muon variables appear correlated to those for the backward proton, as expected by the two-nucleon correlation model. 相似文献
1000.
We discuss productions of scalar gluonium candidates in the radiativeJ/ decays. The branching ratios of such productions are estimated on the basis of the Euler-Heisenberg effective Lagrangian for gluon-photon couplings. We mention that these estimates cannot be expected to be accurate to better than within a factor 2. We show that the radiativeJ/ decays probably invalidate gluoniumgg interpretation of the GAMS meson F0(1590) and a narrow 0++ stateS lying below 1 GeV. However, a possible wide scalar effective gluonium candidate(920) is shown not to be excluded by the data on the decayJ/. We also find that the experimental data about radiativeJ/ decays presumably agree with a recently suggested interpretation of F0(1590) as being approximately a half-and-half mixture of pure 0++ gluoniumgg andSU(3)f singlet quarkoniumq¯q states. 相似文献