bluuebunny/crossref_metadata_2025_split huggingface dataset:
Local Realistic Theory for PDC Experiments Based on the Wigner Formalism
Authors: Casado Alberto , Risco-Delgado Ramón , Santos Emilio 
Published: February 2015

Abstract
In this article we present a local hidden variables model for all experiments involving photon pairs produced in parametric down conversion, based on the Wigner representation of the radiation field. A modification of the standard quantum theory of detection is made in order to give a local realistic explanation of the counting rates in photodetectors. This model involves the existence of a real zeropoint field, such that the vacumm level of radiation lies below the threshold of the detectors.
Coherently Driven Micromaser Pumped by Atoms in Superposition States
Authors: Casagrande F. , Lulli A. , Santagostino V. 
Published: February 2015

Abstract
By a Monte Carlo wave function approach we describe the dynamics of a coherently driven micromaser pumped by coherently prepared atoms. The system can exhibit nonclassical effects such as quadrature squeezing, sub-Poissonian photonstatistics, and Rabi oscillations revival. The interplay between driving field and polarised atoms allows manipulating both the photon number and the phase of the cavity field. By varying either the atomic transit time or the injected field intensity, the coherence of the system dynamics can be enhanced or even suppressed, whereas the induced cavity field phase can be shifted.
Delayed-choice Measurement and Temporal Nonlocality
Authors: Kim Ilki , Mahler Günter 
Published: February 2015

Abstract
We study for a composite quantum system with a quantum Turing architecture the temporal non-locality of quantum mechanics by using the temporal Bell inequality, which will be derived for a discretized network dynamics by identifying the subsystem indices with (discrete) parameter time. However, the direct “observation” of the quantum system will lead to no violation of the temporal Bell inequality and to consistent histories of any subsystem. Its violation can be demonstrated, though, for a delayedchoice measurement
Chaos and Possible Underpinnings for Quantum Mechanics
Authors: McHarris Wm. C. 
Published: February 2015

Abstract
Deterministic chaos with its nonlinearities can formally reproduce some of the counterintuitive idiosyncrasies of quantum mechanics. In this paper I raise the question as to whether chaos might possibly supply some of the “hidden variables” that have been sought as underpinnings at a deeper level of quantum mechanics
Brownian Motion: the Quantum Perspective
Authors: Vacchini Bassano 
Published: February 2015

Abstract
We briefly go through the problem of the quantum description of Brownian motion, concentrating on recent results about the connection between the dynamics of the particle and dynamic structure factor of the medium. - 05.40.Jc, 05.30.Fk, 05.30.Jp, 03.65.Yz
A Neutron and X-ray Diffraction Study of the Structure of Nd Phosphate Glasses
Authors: Hoppe Uwe , Ebendorff-Heidepriem Heike , Neuefeind Jörg , Bowron Daniel T. 
Published: February 2015

Abstract
Diffraction experiments were performed on two (Nd2O3)x(P2O5)1- x glasses for studying the en­ vironmental order of the Nd3+ cations. In case of the metaphosphate glass (x = 0.25) a combination of X-ray and neutron diffraction data was used to separate the Nd-O and O-O first neighbor peaks. An Nd-O coordination number of 6.6±0.3 and a mean Nd-O distance of (0.239±0.001) nm were determined. In the ultraphosphate glass studied (x = 0.20) these values increase to 6.9±0.3 and (0.240±0.001) nm where the Nd-0 coordination number is equal to the number of terminal oxygen atoms (OT) which are available for coordination of each Nd3+ cation. This indicates the formation of NdOn polyhedra not sharing any O atom where also all OT's are in N d-OT-P positions. In the metaphosphate glass the NdOn polyhedra have to share some OT sites.
Phase Transitions and Water Dynamics of [Co(H2O)6](ClO4)2 and [Mn(H2O)6](BF4)2 Studied by Neutron Scattering Methods
Authors: Mikuli E. , Migdał-Mikuli A. , Natkaniec I. , Grad B. 
Published: February 2015

Abstract
Inelastic incoherent neutron scattering (IINS) spectra and neutron powder diffraction (NPD) patterns, registered for [Co(H2O)6](ClO4)2 at 18 -270 K and for [Mn(H2O)6](BF4)2 at 18 -230 K, provided evidence that these crystals possess three solid phases in these ranges of temperatures. In both compounds the phase transition occurring at TC3 is connected with a change of the crystal structure, and that occurring at TC2 with a change in the rate of the reorientational motions of H2O ligands.
Mössbauer Investigation of Eu3+ Site Occupancy and Eu-O Covalency in Y2O3 and Gd2O3 Nanocrystals
Authors: Concas G. , Muntoni C. , Spano G. , Bettinelli M. , Speghini A. 
Published: February 2015

Abstract
Samples of nanocrystalline Y1.8Eu0.2O3 and Gd1.8Eu0.2O3 were examined by 151Eu Mössbauer spectroscopy. The degree of covalency of the Eu-O bond has been studied. The spectrum of the cubic Y1.8Eu0.2O3 sample has been resolved into 2 contributions due to europium in the C3i and C2 sites, for the first time in 151Eu Mössbauer spectroscopy. The degree of covalency and the electric field gradient of the 2 sites has been compared. The occupancy, by the lanthanide ion, of the more and less symmetric sites in the cubic structure of Y1.8Eu0.2O3 has been investigated and discussed.
Molecular Dynamics Simulation of the Internal Mobilities in Molten (Dy1/3,K)Cl
Authors: Matsumiya Masahiko , Takagi Ryuzo 
Published: February 2015

Abstract
Molecular dynamics simulations have been performed on molten (Dy1/3,K)Cl at 1093 K in order to compare the calculated self-exchange velocity (SEV), self-diffusion coefficient (D) and electrical con­ductivity with the corresponding experimental results. It was found that SEV, v, and D of potassium de­ crease with increasing concentration of dysprosium, as expected from the internal mobility, b. The decrease of bK, vK, and DK are ascribed to the tranquilization effect by Dy3+ which strongly inter­ acts with CP. On the contrary, bDy, vDy, and DDy increase with increasing concentration of Dy3+. This may be attributed to the stronger association of Dy3+ with Cl- due to the enhanced charge asym­ metry of the two cations neighboring to the Cl-. In addition, the sequence of the calculated SEV's, D's and electrical conductivities for the various compositions were consistent with those of the referred ex­ perimental results.
Nematogenic Behaviour of a Cyano-Compound Using Quantum Mechanics and Computer Simulations
Authors: Ojha Durga Prasad 
Published: February 2015

Abstract
Using quantum mechanics and intermolecular forces, the molecular ordering of a nematogenic cya-no-compound, 5-(frans-4-ethylcyclohexyl)-2-(4-cyanophenyl)-pyrimidine (ECCPP), has been exam­ ined. The CNDO/2 method has been employed to evaluate the net atomic charge and the dipole mo­ ment components at each atomic centre of the molecule. The configuration energy has been computed using the modified Rayleigh-Schrödinger perturbation method at intervals of 1Ä in translation and 10P in rotations, and corresponding probabilities have been calculated using Maxwell-Boltzmann statistics. The flexibility of various configurations has been studied in terms of the variation of the probability due to small departures from the most probable configuration. All possible geometrical arrangements between a molecular pair have been considered during stacking, in-plane and terminal interactions, and the most favourable configuration of pairing has been obtained. An attempt has been made to under­ stand the behaviour of the molecules in terms of their relative order. The results have been compared with those obtained for other nematogens like DPAB [4,4'-di-n-propoxy-azoxybenzene] and EMBAC [ethyl 4-(4'-methoxybenzylidene amino) cinnamate].
Sub-Doppler Measurements and Terahertz Rotational Spectrum of 12C18O
Authors: Klapper G. , Lewen F. , Gendriesch R. , Belov S. P. , Winnewisser G. 
Published: February 2015

Abstract
The five lowest rotational transitions of 12C180 (J =2 ← 1 to J = 6 ← 5) have been measured by saturation dip spectroscopy with an experimental accuracy of 1 to 1.5 kHz, employing phase-stabilized backward-wave oscillators. The five J rotational transitions cover the frequency range between 219 and 658 GHz. In addition, we have measured in the Doppler limited mode the rotational transitions J = 1 ← 0, J = 7 ← 6 and J = 8 ← 7. The accuracy achieved for the individual frequencies ranges between 5 and 20 kHz. Moreover the three rotational transitions J = 16 ← 15 to J = 18 ← 17 in the frequency region 1.7-2.0 THz were measured with an accuracy of 15 to 30 kHz by using the Cologne side­ band spectrometer for terahertz applications COSSTA.
The Energy of a Graph and its Size Dependence. An Improved Monte Carlo Approach
Authors: Fripertinger Harald , Gutman Ivan , Kerber Adalbert , Kohnertb Axel , Vidović Dusica 
Published: February 2015

Abstract
In an earlier work [Gutman et al., Chem. Phys. Lett. 297, 428 (1998)] the average energy (E) of graphs with n vertices and m edges was examined, in particular its dependence on n and m . The quantity (E) was computed from a set of randomly, but not uniformly, constructed (n ,m)-graphs. We have now improved our method by constructing the (n,m)-graphs uniformly, so that every (n , m)-graph has equal probability to be generated. Differences between the old and new approaches are significant only in the case of graphs with a small number of edges.
Nematogenic Behaviour of EPPV in a Dielectric Medium. A Theoretical Study
Authors: Ojha Durga Prasad 
Published: February 2015

Abstract
4-(4/-ethoxyphenylazo) phenyl valerate (EPPV) is a nematic liquid crystal, which shows a nematic mesophase at 352 K and becomes an isotropic melt at 401 K. A theoretical study of the molecular order­ ing has been carried out on the basis of intermolecular interaction energy calculations. The CNDO/2 method has been employed to compute the net atomic charge and atomic dipole components at each atom­ ic centre of the molecule. Modified Rayleigh-Schrödinger perturbation treatment has been employed to calculate the interaction energy between a molecular pair. The probability of the occurrence of a partic­ ular configuration in a dielectric medium has been calculated using the Maxwell-Boltzmann formula. The flexibility of various configurations has been studied in terms of the variation of the probability due to a small departure from the most probable configurations. On the basis of stacking, in-plane and terminal interactions, all possible geometrical arrangements between a molecular pair have been considered, and the most favourable configuration of pairing has been obtained. An attempt has been made to explain the nematogenic behaviour of liquid crystals based on the parameters introduced in this paper.
Static and Dynamic Structure of Molecular Monomers and Dimers of the Rare-earth Fluorides
Authors: Akdeniz Z. , Gaune-Escard M . , Tosi M. P. 
Published: February 2015

Abstract
We determine a model of the ionic interactions in RF3 compounds, where R is a rare-earth element in the series from La to Lu, by an analysis of data on the bond length and the vibrational mode frequencies of the PrF3, GdF3 and HoF3 molecular monomers. All RF3 monomers are predicted to have a pyramidal shape, displaying a progressive flattening of the molecular shape in parallel with the lanthanide contraction of the bond length. The vibrational frequencies of all monomers are calculated, the results being in good agreement with the data from infrared studies of matrix-isolated molecules. We also evaluate the geometrical structure and the vibrational spectrum of the La2F6 and Ce2F6 dimers, as a further test of the proposed model. -PACS 36.40.Wa (Charged clusters)
Structural Studies on Substituted N-(phenyl)-2,2-DichIoroacetamides, 2/4-XC6H4 NHCO CHCI2 (X = H, Cl or CH3)
Authors: Gowda B. Thimme , Paulus Helmut , Fuess Hartmut 
Published: February 2015

Abstract
The effect of substitution in the phenyl ring on the crystal systems of amides of the type, 2/4-XC6H4-NHCO-CHCl2 (X = H, Cl or CH3), has been studied by determining the crystal structures of the compounds, iV-(phenyl)-2,2-dichloroacetamide, C6H5-NHCO-CHCl2 (PhDCA); N-(2-chlorophenyl)-2,2-dichloroacetamide, 2-ClC6H4-NHCO-CHCl2 (o-ClPhDCA), jY-(4-chlorophenyl)-2,2-dichloroacetamide, 4-ClC6H4-NHCO-CHCl2 (p-ClPhDCA) and N -(4-methylphenyl)-2,2-dichloroacetamide, 4-CH3C6H4-NHCO-CHCl2 (p-CH3PhDCA) and analysed the data along with our earlier crystal structures of the compounds, N-(phenyl)-2,2,2-trichloro-acetamide (PhTCA), N-(2-chlorophenyl)-2,2,2-trichloroacetamide (o-ClPhTCA), N -(4-chloro-phenyl)-2,2,2-trichloroacetamide (p-ClPhTCA), N-(4-methylphenyl)-2,2,2-trichloroacetamide (p-CH3PhTCA); N-chloro-N-(phenyl)-2,2-dichloroacetamide (NClPhDCA), N-chloro-N-(phenyl)-2,2,2-trichloroacetamide (NClPhTCA) and N-(phenyl) acetamide (PhA). The crystal type, space group, formula units and lattice constants in A of the new structures are; PhDCA: monoclinic, P 21/c, Z = 4, a = 8.785(3), b = 11.139(4), c = 9.521(3), ß = 97.47(2)°; o-CIPhDCA: monoclinic, P 21/c, Z = 4, a = 4.711(2), b = 11.234(6), c = 19.191(8), ß = 98.12(2)°; p-CIPhDCA: monoclinic, P 21/c, Z = 8, a = 18.627(5), b = 11.533(3), c = 9.583(3), ß = 102.43(2)°, and /?-CH3PhDCA: orthorhombic, Pbca, Z = 8, a = 9.464(3), b = 9.894(3), c = 21.973(7). The compound p-ClPhDCA shows two molecules in its asymmetric unit. This is in agreement with the multiple lines observed in the 35Cl NQR spectra of the compound. The crystal systems of the chlorosubstituted and methyl substituted chloroacetamides get interchanged on replacement of the side chain -CHCl2 by -CCl3. C(i)-C(j) ring distances show no significant variations with the substitution either at the side chain or in the phenyl ring. C(ring)-N and C (0)-N bond distances are also not much affected by either ring or side chain substitution, but are affected by N-chlorination, while the C -0 bond length is slightly shortened by the replacement of the -CH3 group by -CCl3, the introduction of electron withdrawing group into the phenyl ring or by N-chlorination. Deviations of C2(ring)-Cl(ring)-N, C6(ring)-Cl(ring)-N and C (ring)-N-C(0) bond angles from 120° narrow down on substitution either in the phenyl ring or in the side chain, but the latter increases on W-chlorination of the compounds.
Revisiting Julg's Structural Approach to Aromaticity
Authors: Giambiagi Myriam S. de , Giambiagi Mario , Figueiredo Aloysio Paiva de 
Published: February 2015

Abstract
Julg's classical formula for aromaticity is updated so as to involve bond indices. A simple CNDO/2 calculation is shown to account satisfactorily for heterocyclic typical rings and other mis­cellaneous systems. Results are compared with a multicenter MO bond index recently introduced as an aromaticity measure.
Magnetohydrodynamic Stability of Two Streaming Superposed Viscoelastic Conducting Fluids
Authors: El Mohamed Fahmy 
Published: February 2015

Abstract
The stability of the plane interface separating two Oldroydian viscoelastic superposed moving fluids of uniform densities when immersed in a uniform horizontal magnetic field has been in­ vestigated. The stability analysis has been carried out, for mathematical simplicity, for two highly viscous fluids of equal kinematic viscosities. It is found that the potentially stable configuration remains stable if the fluids are at rest, while it becomes unstable if the fluids move. The stability criterion is found to be independent of the viscosity and viscoelasticity, and to be dependent on the orientation of the magnetic field and the magnitudes of the fluids and Alfven velocities. It is also found that the potentially unstable configuration remains unstable in the absence of average fluid velocities, or in the presence of fluid velocities and absence of a magnetic field. The magnetic field is found to stabilize a certain wavenumbers range of the unstable configuration even in the presence of the effects of viscoelasticity. The behaviour of growth rates with respect to the stress relaxation time, strain retardation time, fluid and Alfven velocity parameters is examined analytically, and the stability conditions are obtained and discussed. -Pacs: 47.20.-k; 47.50.+d; 47.65.+a.
Media Effect upon the Fluorescence Ability of Differently Substituted α-Cyanostilbenes
Authors: Nikolov Peter , Petkova Irina , Stoyanov Stefan 
Published: February 2015

Abstract
The steady state and dynamic photophysical characteristics of α-cyanostilbene derivatives have been investigated in solution and in Polyvinylchloride (PVC) film at 300 K as well as in a frozen matrix at 77 K. While no emission is observed in solution, a significant fluorescence ability is registered both in PVC and frozen media. This fact is attributed to the matrix effect, which lessens the possible intramolecular motions around the central double bond. No phosphorescence at 77 K is observed. The fluorescence lifetimes at 77 K are compared with literature data for similar chemically fixed structures.
Electronic Spectral Investigations upon the Photochemical Transformations of Some Substituted 1-(N,N-bisacyl)amino-4,5-diphenyl-l,2,3-triazoles
Authors: Petkova Irina , Maroulis Apostolos J. , Hadjiantoniou-Maroulis Constantina , Nikolov Peter 
Published: February 2015

Abstract
The objective of this report is to investigate the steady state and dynamic photophysical and photochemical properties of 1-(N,N-bisacyl)amino-4,5-diphenyl-1,2,3-triazoles in solvents of dif­ferent polarity at room temperature and in frozen matrix at 77 K. On the basis of the comparison of their UV absorption and luminescence spectra with those of 4,5-diphenyl-1,2,3-triazole and diben-zamide (model compounds), cleavage of the N-N bond in the title compounds after irradiation with polychrome UV light is proved.
A Molecular Dynamics Simulation of the Electric and Thermodynamic Properties in Molten (Nd1/3, Na or K)Cl Mixtures
Authors: Matsumiya Masahiko , Takagi Ryuzo 
Published: February 2015

Abstract
Molecular dynamics simulations have been carried out on molten (Nd1/3, K)Cl at 1065 and 1073 K and (Nd1/3, Na)Cl at 1124 K for various compositions. The calculated self-exchange velocity (v ), self-diffusion coefficient (D), electrical conductivity (k) and enthalpy of mixing ( ΔHmix) were compared with the corresponding experimental values. The calculated results revealed that v and D of potassium decrease with increasing anmount of neodymium, as expected from the experimental internal mobility (6). The decrease of bK, vK, and DK are attributed to the tranquilization effect by Nd3+ which strongly interacts with Cl- as well as Dy3+. On the contrary, bNd, VNd, and DNd increase with increasing concentration of Nd3+. This might be ascribed to the stronger association of Nd3+ with Cl- due to the enhanced charge asymmetry of the two cations neighboring Cl- . In addition, the sequences of the calculated v's, D's and k ’s for the various compositions were consistent with those of the known experimental results. The experimental enthalpy of mixing with its negative dependence on the cation size was qualitatively reproduced.
Defect Structures for Fe3+, Mn2+, and Ni3+ Impurities in Wuritzite GaN Crystals
Authors: Zheng Wen-Chen , Wu Shao-Yi , Zi Jian 
Published: February 2015

Abstract
Electron paramagnetic resonance (EPR) zero-field splittings D for Mn2+ and Fe3+ in wurtzite GaN crystals are studied from high-order perturbation formulas based on the spin-orbit mechanism in both weak- and strong-field schemes. From these studies it can be seen that the Mn2+ or Fe3+ impurity does not occupy the exact Ga3+ position, but is displaced by ΔR on the C3 axis. The displacements are confirmed from a study of the superposition model, based on which a normal value of b̅2 (Ro) ( ≈ -0 .34 (15) cm-1 ) for the Fe3+-N3- combination is suggested. The EPR parameters D, g|| and g ⟂ for Ni3+ in GaN crystals are also studied. It is found that Ni3+ is almost not displaced. The impurity displacements in GaN are discussed by considering the valences and radii of these impurity ions and the replaced Ga3+ ion. - Pacs: 61.16Hn; 76.30Fc; 71.70Ch
An X-ray and Neutron Scattering Study of the Structure of Zinc Vanadate Glasses
Authors: Hoppe Uwe , Kranold Rainer , Gattef Emil , Neuefeind Jörg , Keen David A. 
Published: February 2015

Abstract
The short-range order of vitreous V20 5 and of three (Zn0)Jt(V20 5)1_x glasses with x = 0.2, 0.4, and 0.5 is studied by X-ray and neutron diffraction experiments where the change of the contrast allows to resolve the V -0 and Z n -0 correlations. The V -0 and the Z n -0 first-neighbor peaks are approximat­ ed by several Gaussian functions. In case of vitreous V20 5 two obvious V -0 distances exist which are related with V 0 4 and V 0 5 units. With ZnO additions the V -O coordination number decreases from 4.4 in vitreous V20 5 to 4.0 in the metavanadate glass where the strongest decrease of the fraction of V 0 5 units is found for glasses of * < 0.2. Dominantly, the V 0 5 groups are linked with the neighboring units by comers. The Z n-0 coordination numbers of the modified glasses are about five with closest dis­ tances of = 0.200 nm.
Frequencies and Normal Modes of Benz(a)anthracene. A MINDO/3-FORCES Treatment
Authors: Kubba Rehab M. , Shanshal Muthana 
Published: February 2015

Abstract
Quantum mechanical calculations, based on the MINDO/3-FORCES method, of the vibration fre­quencies and IR absorption intensities of benz(a)anthracene are reported and compared with calculated vibration frequencies of that molecule. For the first time a complete normal coordinate analysis for the molecule is reported. Interesting correlations between vibration motions of the same type but different symmetries are reported.
Vibration Frequencies and Normal Coordinates of Benzo(c)phenanthrene
Authors: Kubba Rehab M. , Shanshal Muthana 
Published: February 2015

Abstract
MINDO/3-FORCES quantum mechanical calculations yielded non-planar (C2) geometry of Ben-zo(c)phenanthrene. The result agrees with the majority of published results but disagrees with others in which a planar (C2 V) structure was accepted in order to simplify the analysis of certain spectroscopic data. Vibration frequencies and IR absorption intensities were calculated then, applying the non-planar (C2) structure. A complete normal coordinate analysis for the molecule is reported. Inspection of these coordinates allowed the discovery of some useful comparative relations between them, which are re­ ported in the paper.
Motions of Ethylammonium Ions in Solid Ethylammonium Chloranilate Studied by 1H Nuclear Magnetic Resonance
Authors: Ishida Hiroyuki , Kumagae Naoki , Sato Setsuko 
Published: February 2015

Abstract
The motions of the ethylammonium ion in solid ethylammonium chloranilate, C2H5NH+
3 • C6HO4CI-
2, are studied by 1H NMR second moment (M2) and spin-lattice relaxation time {T1) measurements. Re­ orientations of the CH3 group about the C-C bond axis and the NH+
3 group about C -N bond axis were observed and their motional parameters were evaluated. The internal rotational barriers of the CH3 and NH+
3 groups of an isolated C2H5NH+
3 ion were estimated from ab initio molecular orbital calculations.