bluuebunny/crossref_metadata_2025 huggingface dataset:
Structures and electron affinities of indole–(water)N clusters
Authors: Carles S. , Desfrançois C. , Schermann J. P. , Smith D. M. A. , Adamowicz L.
Published: July 2002

Rydberg electron transfer spectroscopy (RET) has been used to determine the dipole-bound electron affinity of the indole molecule, and the value of 3 meV was obtained. RET has also been employed to study [indole–(water)N]− cluster anions and the results have been interpreted with the help of ab initio calculations. It has been shown that for N=1 and 2 only dipole-bound anions are formed and that the electron attachment induces large amplitude motions in these systems. [Indole–(water)N]− anions with N=3 and 4 have not been observed. This finding for N=3 is consistent with a low theoretically predicted dipole moment of the neutral indole–(water)3 complex, which is insufficient for the formation of a stable dipole-bound anion. Above N=5, RET experiments showed formation of valence [indole–(water)N]− anions. From the observed size threshold for the formation of these anions, the negative value of the valence electron affinity of indole equal to −1.03±0.05 meV was deduced.
Direct ab initio quantum scattering for the H2+OH→H+H2O reaction using Møller–Plesset fourth order perturbation theory
Authors: Yu Hua-Gen , Nyman Gunnar
Published: July 2002

We present a realistic ab initio quantum scattering (AIQS) calculation for the chemical reaction H2+OH→H+H2O using the rotating bond approximation (RBA), based on a dual-level MP4//SAC (the fourth order Møller–Plesset perturbation theory/scaling all correlation) method with the 6-311+G(d,p) basis set. The MP4//SAC results give a vibrationally adiabatic ground state barrier height of 0.2722 eV. Calculated thermal rate constants are in good agreement with experimental measurements.
Rotational dynamics of rodlike polymers in a rod/sphere mixture
Authors: Phalakornkul J. K. , Gast A. P. , Pecora R.
Published: July 2002

Transient electric birefringence decay studies of the rotation of rodlike polymers in solutions with spherical particles have been performed as a function of the sphere volume fraction. The rodlike polymers are helical poly-γ-benzyl, α-L-glutamates of several lengths. The spheres are coated silica particles and the solvent is a mixture of dimethyl formamide and pyridine that matches the refractive index of the spheres. The rotation of the relatively dilute rods is systematically studied as a function of the sphere concentration. In the suspension where the rods are shorter than the average sphere diameter, the rotational relaxation rate changes only slightly from the relaxation rate of pure rods in the same solvent. In the suspensions of longer rods, the rotation rate decreases rapidly as the sphere concentration increases and scales with the rod length and sphere concentration. We develop a scaling model by combining our results on rod rotation in a rod/solvent dispersion [J. K. Phalakornkul et al., Macromolecules 32, 3122 (1999)] and our experimental results on mutual diffusion of the spheres [J. K. Phalakornkul et al., Phys. Rev. E 54, 1(1996)], to determine the dependence of the rod rotation rate on the sphere concentration. The scaling exponent of the rod rotational time with rod length shows a weaker dependence on length than the scaling model prediction. We measured the viscosities of the sphere dispersions. The rotational relaxation time is not simply related to the background sphere suspension viscosity.
Electronic properties of mixed barium–oxygen clusters
Authors: Boutou V. , Lebeault M. A. , Allouche A. R. , Paulig F. , Viallon J. , Bordas C. , Chevaleyre J.
Published: July 2002

Ionization potentials of BanOm clusters (2⩽n⩽13,m⩽n) have been measured by one photon ionization. These measurements, combined with relative abundances observed in mass spectra recorded under low (direct ionization) and high (dissociative ionization) laser intensity, allow to derive general trends in the evolution of the structure and stability of barium–oxide clusters. Stoichiometric clusters (BaO)n exhibit a very fast transition toward the ionic bulk barium–oxide structure while suboxides BanOn−1 exhibit a completely different behavior. In the small size range (n<9,m<5), the evolution of the electronic properties does not show any regular behavior. In particular, BanO3 present very low ionization potentials while, on the opposite, the ionization potentials of BanO4 clusters are relatively high. On the other hand, beyond n⩾9, the evolution of the electronic properties is rather smooth and a specific structural transition is observed when the oxygen/barium ratio increases.
Evaluation of charge penetration between distributed multipolar expansions
Authors: Freitag Mark A. , Gordon Mark S. , Jensen Jan H. , Stevens Walter J.
Published: July 2002

A formula to calculate the charge penetration energy that results when two charge densities overlap has been derived for molecules described by an effective fragment potential (EFP). The method has been compared with the ab initio charge penetration, taken to be the difference between the electrostatic energy from a Morokuma analysis and Stone’s Distributed Multipole Analysis. The average absolute difference between the EFP method and the ab initio charge penetration for dimers of methanol, acetonitrile, acetone, DMSO, and dichloromethane at their respective equilibrium geometries is 0.32 kcal mol−1.
The vibrational spectrum of deuterated phosphaethyne: A quantum mechanical, classical, and semiclassical analysis
Authors: Bredenbeck J. , Beck C. , Schinke R. , Koput J. , Stamatiadis S. , Farantos S. C. , Joyeux M.
Published: July 2002

The vibrational spectrum of deuterated phosphaethyne (DCP) is analyzed in terms of quantum-mechanical variational calculations, classical mechanics (periodic orbits), and an effective Hamiltonian model. The quantum mechanical and classical calculations are performed with a new, spectroscopically accurate potential energy surface. The spectrum is governed by a 2 : 1 DC stretch : CP stretch anharmonic resonance, which already exists for the fundamentals. The bending degree of freedom is to a large extent decoupled. It is shown that several bifurcations in the classical phase space profoundly influence the quantum spectrum. For example, a new progression, which does not exist at very low excitation energies, comes into existence at intermediate energies. In contrast to HCP, the pure bending states gradually evolve along the isomerization path with increasing bending quantum number.
Theoretical study of valence photoelectron spectrum of OsO4: A spin-orbit RESC-CASPT2 study
Authors: Nakajima Takahito , Koga Katsumichi , Hirao Kimihiko
Published: July 2002

The valence photoelectron spectrum (bands from A to E) of OsO4 is studied by second-order complete active space perturbation theory (CASPT2). The relativistic effects are included by the relativistic elimination of the small components (RESC) scheme. Spin-orbit coupling is also considered. Both the electron correlation and relativistic effects are significant on the peak position and intensity of valence photoelectron spectrum of OsO4. RESC-CASPT2 gives values for the peak position and intensity in reasonable agreement with the resolved photoelectron spectrum data. The state ordering is predicted as T12(1t1)>2T2(3t2)>2A1(2a1)>2T2(2t2)>2E2(1e). Electron correlation shifts all peak positions by 2.5–3.5 eV to the high-energy side. Spin-free relativistic effects shift the band D by 0.8 eV again to the high-energy side due to the stabilization of Os 6s orbital. The present study confirms that the band C arises from the spin-orbit coupling in the ionic T22(3t2) state. Under the E band, there are many two-electron shake-up peaks in addition to the two one-electron ionization peaks. The broad feature of the E band is due to the satellite peaks and can be well explained through the introduction of the relativistic effects.
Directions of transition dipole moments of t-butyl nitrite obtained via orientation with a strong, uniform electric field
Authors: Castle Karen J. , Kong Wei
Published: July 2002

A strong, uniform electric field was used to orient supersonically cooled t-butyl nitrite for measurements of directions of transition dipole moments. The oriented sample was dissociated with linearly polarized light, and the NO fragments were studied by (1+1) REMPI through the A 2Σ+ state. At photolysis wavelengths of 365.8 and 351.8 nm, there was a 47% enhancement in the NO signal when the photolysis beam was polarized perpendicular to the orientation field, implying a perpendicular relationship between the transition dipole of the S1 state and the permanent dipole. Photodissociation at 250 and 224 nm showed the opposite trend, with a 46% enhancement in the NO signal when the photolysis beam was polarized parallel to the orientation field. The transition dipole of the S2 state was therefore determined to be parallel to the permanent dipole. This experiment demonstrates the application of brute force orientation for obtaining directions of transition dipole moments.
Reduced dimensionality wave packet study of the NH3++H2, D2 reaction
Authors: Aguillon F. , Sizun M.
Published: July 2002

The reaction between NH3+ and D2 (or H2), leading to NH3D++D (or NH4++H) is investigated using a quantum wave packet approach at a collision energy below 2.5 eV. The study is restricted to the collinear geometry preserving C3v symmetry. Three degrees of freedom are explicitly treated: the reactive D–D and N–D distances, and the umbrella angle of NH3. The effects of the initial vibrational excitation of D2 (or H2) and of the umbrella motion of NH3+ are studied. The reaction probability is found to be large and to decrease with internal excitation of the reagents. The state-to-state reaction probabilities for the two isotopic variants differ qualitatively. This is related to the existence of a Fermi resonance in the geometrically constrained NH4+ ion, which does not exist in NH3D+. The umbrella motion is found to play an active role in the reactivity at a collision energy above 1 eV.
The correlation between local and long-range structure in compressible supercritical fluids
Authors: Goodyear Grant , Maddox Michael W. , Tucker Susan C.
Published: July 2002

We derive a family of local-density-specific radial distribution functions which enable us to analyze the fluid structure around a tagged solvent particle as a function of the local environment about that particle. With this new structural measure, we uncover a very strong correlation between the local density around a tagged atom and the surrounding long-range fluid structure in a neat, two-dimensional, Lennard-Jones fluid at a compressible supercritical state point. Indeed, we show that such an environmentally specific measure of structure provides an informative probe of compressible supercritical fluids, within which the distribution of accessible local solvent environments is typically very broad. Additionally, we find that these new functions provide a more sensitive measure of the mean size of the density inhomogeneities than does the correlation length, and thus that they provide an effective indicator of simulation convergence for molecular dynamics simulations performed in the supercritical regime.
Search for precursor of pressure-induced amorphization of molecular crystal SnI4: Thermodynamic stability of low-pressure crystalline phase
Authors: Fuchizaki Kazuhiro , Sugiyama Shuichi , Fujii Yasuhiko
Published: July 2002

The pressure–temperature phase diagram of SnI4 was investigated to examine the inherent instability of crystalline SnI4 in terms of undergoing pressure-induced solid state amorphization, by conducting molecular dynamics simulations prior to studies involving laboratory experiments. The SnI4 molecules are regarded as rigid tetrahedra interacting with one another via van der Waals forces. In order for the isothermal–isobaric ensemble to be achieved, the well-established Nosé–Klein scheme combined with the momentum scaling method was adopted when carrying out the simulations. The system was carefully heated up under fixed hydrostatic pressure from the low-pressure crystalline state across the melting point, which was determined by monitoring the time-dependence of the mean square displacement of the molecules, whereas, on cooling, the liquid state remained supercooled down to room temperature. The slope of the liquidus in the phase diagram between the low-pressure crystalline phase and the liquid phase was found to be positive, implying that the low-pressure crystalline phase has little connection with solid state amorphization. An expected overall pressure–temperature phase diagram of SnI4 is discussed.
Linear and nonlinear dielectric constant tensor for monolayer films in terms of orientational order parameters
Authors: Wu Chen-Xu , Zhao Wei , Iwamoto Mitsumasa , Zhong-can Ou-Yang
Published: July 2002

We give a general expression of the dielectric constant tensor in orientational orders in the applied static or low-frequency electric field for the semi-two-dimensional monolayer films with C∞v symmetry. The dielectric anisotropic orientational tensor and orientational polarization tensor are derived in orientational order parameters. The nonlinear electro-optical Pockels effect including the local-field influence is also discussed using the orientational orders. A numerical calculation result shows that the first orientational order parameter S1 is a destructive order while the second orientational orientational order parameter S2 is a constructive one to the dielectric constant in the normal direction of monolayer films.
Orientation and nonlinear optical properties of 4-(N,N-dimethylamino)-3-acetamidonitrobenzene crystals on nanostructured poly(tetrafluoroethylene) substrates
Authors: Vallée R. , Damman P. , Dosière M. , Toussaere E. , Zyss J.
Published: July 2002

The growth of 4-(N,N-dimethylamino)-3-acetamidonitrobenzene (DAN) crystals on nanostructured poly(tetrafluoroethylene) (PTFE) substrates has been investigated by means of x-ray, micro-FTIR (Fourier-transform infrared) and nonlinear optical ellipsometry techniques. Two types of structural arrangements were identified, depending on growth conditions. In both cases, the (001)DAN plane contacts the (100)PTFE substrate plane. The major difference between both types of samples lies in the degree of azimuthal orientation at the interface. For thin samples (thickness<0.3 μm), the average direction of the a crystallographic axes of the DAN crystals lies parallel to the [001]PTFE direction with a broad angular distribution, while thick samples (thickness>1 μm) are characterized by a uniaxial orientation with an isotropic random distribution in the plane of the layers. The comparison between various techniques used in this study to characterize the obtained thin films showed a remarkable agreement. In this context, second-harmonic generation was revealed once again as a powerful technique toward the study of orientation effects in crystalline layers of NLO organic materials, much beyond the possibilities of traditional linear polarization methods.
Fluctuations in mixtures of lamellar- and nonlamellar-forming lipids
Authors: Li Xiao-jun , Schick M.
Published: July 2002

We consider the role of nonlamellar-forming lipids in biological membranes by examining fluctuations, within the random phase approximation, of a model mixture of two lipids, one of which forms lamellar phases while the other forms inverted hexagonal phases. To determine the extent to which nonlamellar-forming lipids facilitate the formation of nonlamellar structures in lipid mixtures, we examine the fluctuation modes and various correlation functions in the lamellar phase of the mixture. To highlight the role fluctuations can play, we focus on the lamellar phase near its limit of stability. Our results indicate that in the initial stages of the transition, undulations appear in the lamellae occupied by the tails, and that the nonlamellar-forming lipid dominates these undulations. The lamellae occupied by the head groups pinch off to make the tubes of the hexagonal phase. Examination of different correlations and susceptibilities makes quantitative the dominant role of the nonlamellar-forming lipids.
Comment on “The surplus function approach” [J. Chem. Phys. 110, 3703 (1999)]
Authors: Marmorino M. G.
Published: July 2002

The surplus function approach was recently introduced as an iterative method to calculate the energies and eigenfunctions of the Schrodinger equation. We remark that the surplus function approach does not necessarily yield ground-state solutions and that some of the integrals needed in this method may not even exist.
Observation and analysis of nonlinear vibrational relaxation of large molecules in shock waves
Authors: Kiefer John H. , Buzyna Leonid L. , Dib Amal , Sundaram Sekhar
Published: July 2002

We report the observation of highly nonlinear vibrational relaxation for a number of large molecules in shock waves, together with an attempt at a master-equation modeling of this phenomenon. In all these molecules laser-schlieren measurements show a clear and often well-resolved local maximum in the density gradient, indicating a similar maximum in the rate of energy transfer. This unexpected phenomenon is seen in the relaxation of benzene (C6H6), cubane (C8H8), cyclopropane (C3H6), furan (C4H4O), norbornadiene (C7H8), oxirane (C2H4O), and quadricyclane (C7H8). It has also been detected in cyclopentadiene (C5H6) and pyrazine (C4N2H4), as well as CF3Br and CF3Cl but in these was not well resolved. The phenomenon thus seems nearly ubiquitous; of the “large” molecules where relaxation could be resolved, only norbornene (at C7H10 the largest such molecule) exhibits a fully linear relaxation. The gradients are clearly and solely from vibrational relaxation; integrated gradients are in good agreement with thermodynamic calculations of total density change, and near-equilibrium relaxation times in pure cyclopropane and oxirane are fully consistent with overlapping ultrasonic results. It appears we are seeing a delay in the development of series coupling in these experiments. An attempt is made to model the process using a linear master equation with exponential gap probabilities having an α(∼〈ΔE〉down) linear in energy. Although this does introduce sufficient nonlinearity through the rate coefficients to produce maxima, these and the overall gradients are consistently too small. It is suggested that inclusion of a true nonlinearity through VV transfer will be needed to explain the observations, and a possible mechanism for this is proposed.
Perturbation in the V 1B2 state of CS2 and the effects of an applied magnetic field
Authors: Kasahara Shunji , Fujita Nobuyuki , Kimura Yasuyuki , Katô Hajime , Baba Masaaki , Nagakura Saburo
Published: July 2002

The excitation spectra of the 15V 31 344.9 band of the CS2 V 1B2←X 1Σg+ transition and the changes in these spectra with the application of a magnetic field of up to 12 kG have been measured with sub-Doppler resolution. The radiative lifetimes of rotationally resolved single lines and single Zeeman components were measured under collision-free conditions. All of the fluorescence decays were observed to be of a single exponential. Large Zeeman splittings were observed for many lines. The only symmetry allowed spin–orbit interaction is that of the A23(B2) component with the B21 state. The A23(B2) component has no magnetic moment, but a magnetic moment is induced when it is mixed with the A23(A1,B1) components. The mixing of the A23(B2) and A23(A1,B1) components is facilitated by spin–rotation interaction and the Zeeman interaction. From analysis of the observed Zeeman splittings of the perturbed levels, the A23(B2) component was determined to lie 14 cm−1 below the nearly degenerate A23(A1) and A23(B1) components in the energy region where the 15V band is observed. Irregular energy shifts and splittings of rotational lines were observed, and these were attributed to (a) Coriolis interaction between the V1B2(v′(a1);K=0JM) and V 1B2(v(b2);K=1JM) levels and (b) resonant spin–orbit interaction between the rotational levels V 1B2(v′(a1);KJM) and R 3A2(v(a1);KJM). These interactions become appreciable when two levels lie close in energy. Large Zeeman splittings were observed in case (b). Many vibrational lines with irregular intensity and spacing were observed in each band. These were attributed to (c) Fermi resonance between the vibrational levels in the V 1B2 state and (d) resonant spin–orbit interaction between vibrational levels in the V 1B2 and R 3A2 states. In case (d), large Zeeman splittings were observed for a series of rotational lines in a vibrational band. The background lines were identified from observed Zeeman splittings as the transitions to levels of the R 3A2 state, which are induced by resonant spin–orbit interaction with the levels of the V 1B2 state. The intensity of the excitation spectrum of the V 1B2←X1Σg+ transition was observed to decrease as the magnetic field increases. This was attributed to a mixing of the A23 state with the V 1B2 state and the resulting triplet–triplet emission, which was not detected in this experiment. It was possible to evaluate the lifetime of the radiative triplet–triplet emission via deperturbation analysis of the perturbed lines.
Photolysis of NO2 excited below the dissociative limit
Authors: Makarov Vladimir I. , Khmelinskii Igor V. , Kochubei Sergei A. , Ishchenko Valerii N.
Published: July 2002

The intermediate LIF spectra were observed and compared in the NO2 (λexc>400 nm) and ClONO2 (λexc=308 nm) photolyses. Both spectra could be assigned to the same transient. Transient fluorescence spectra were recorded in the 12 500–16 400 cm−1 range at λexc=436.45 nm. Analysis shows that the observed intermediate spectra can be attributed to the NO3 radical. The NO3 lifetime variations in the presence of CF4, CF3Cl, CF2Cl2, CFCl3, and CCl4 were also studied. It was shown that these compounds only influence the photolysis yield of NO3, without affecting its lifetime. The magnetic field influence on the discrete and total NO2 fluorescence, and on the NO3 radical yield were also measured using λexc=436.45, 458.13, 478.93, and 489.12 nm.
A comparative study of the quantum dynamics and rate constants of the O(3P)+HCl reaction described by two potential surfaces
Authors: Skokov Sergei , Tsuchida Tomoki , Nanbu Shinkoh , Bowman Joel M. , Gray Stephen K.
Published: July 2002

Wave packet calculations, using direct and damped-L2 real propagation methods, of initial state-resolved and cumulative reaction probabilities for the O(3P)+HCl(1Σ+)→OH(2Π)+Cl(2P) reaction are reported. Results are obtained using the recently developed “S4” potential surface of Ramachandran and co-workers and, for comparison, the earlier Koizumi, Schatz, and Gordon (KSG) potential energy surface. Most calculations are for total angular momentum J=0, although some J>0 centrifugal sudden results are also obtained. The thermal rate constant and the rate constant for HCl(v=1) are obtained from the J=0 cumulative reaction probability and J-K-shifting, using standard transition-state rotation constants. This type of shifting is justified by examining limited centrifugal sudden calculations. The S4 surface is shown to yield some surprising results. For example, despite a significantly higher ground state adiabatic barrier than the KSG surface, the thermal rate constant is not significantly different from one obtained with the KSG surface, although the one for the vibrationally excited HCl is.
Effect of polydispersity on the evolution of density fluctuations to lamellar crystals in linear polyethylene
Authors: Akpalu Yvonne A. , Amis Eric J.
Published: July 2002

The effect of polydispersity on structure development in linear polyethylenes is studied by simultaneous real time small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering (WAXS). Our measurements show that below 128 °C, changes in the SAXS and WAXS intensity profiles for a broad molecular-weight distribution sample occur simultaneously as previously reported for a narrow molecular-weight distribution sample. We demonstrate that variations in the SAXS profile can be correlated with the morphological changes associated with the evolution of single chain folded crystal lamellae to lamellar aggregates. At 128 °C and higher temperatures, changes in the SAXS intensity profile for the broad molecular weight distribution sample occur much earlier than the onset of lamellar crystal growth evidenced in the WAXS profile. For the period before crystal growth is manifest in the WAXS scattering, the SAXS intensity at low angles increases while the domain size remains constant. The low-angle intensity uptake in SAXS can be best described by the Guinier approximation. On the other hand, the temperature dependence of the variation in the average crystal thickness during isothermal crystal growth is a function of the relative rates of primary crystallization and thickening at a given temperature. We discuss the effect of a broad distribution in chain length on the various stages in the development of the morphology.
Quantum defect theory of the molecular photoabsorption process: NO spectra in the energy region 9.3–22.0 eV
Authors: Zhong Zhi Ping , Zhang Wei Hua , Li Jia-Ming
Published: July 2002

The vacuum ultraviolet photoabsorption spectra of NO are calculated by the multiscattering self-consistent-field method and all the excited states are treated in a unified manner in the framework of quantum defect theory. With the calculated results we provide clear assignments for the experimental spectra in the energy region of 9.3–22.0 eV, and then obtain corresponding excitation energies and optical oscillator strengths for electronic transitions. Our calculated values are in good agreement with the available experimental data. In addition, we have determined the photodissociation and photoionization oscillator strengths for B 2Π, L 2Π, and 4 2Π, respectively from the available experimental spectra.
An efficient calculation of the energy levels of the carbon group
Authors: Zheng Nengwu , Ma Dongxia , Yang Ruyi , Zhou Tao , Wang Tao , Han Song
Published: July 2002

Energy levels of many-valence-electron atomic (ionic) systems play an important role in many scientific disciplines. Many theoretical methods to calculate the energy levels of Rydberg states of atoms and ions have been provided, and the carbon group atoms have been treated. In this paper, we computed single excited states of carbon group atoms with high precision. The accuracy of most of our results that have been reached are less than 1 cm−1. This is quite good among all the present theoretical methods.
Photodissociation dynamics of the propargyl bromide molecular ion
Authors: Kim Doo Young , Choe Joong Chul , Kim Myung Soo
Published: July 2002

Photodissociation of the propargyl bromide molecular ion has been investigated using mass-analyzed ion kinetic energy spectrometry (MIKES). The MIKE spectra for the bromine loss has been measured as a function of the laser polarization angle at 357, 488.0, 514.5, and 607.5 nm. A convenient analytic method to treat the MIKE profile has been developed and the anisotropy parameters and kinetic energy release distributions (KERDs) have been determined by analyzing the experimental data. At all the wavelengths used, an anisotropic dissociation in the repulsive excited electronic state(s) has been observed. In addition, the statistical dissociation in the ground electronic state has been observed at 357 and 607.5 nm. Results from quantum chemical calculations carried out at the TDDFT/UB3LYP level using the 6-311++G** basis set will be discussed in relation to the nature of the repulsive excited electronic state involved.
Vibration–rotation fluorescence spectra of water in the ground electronic state
Authors: Nela Maria , Permogorov Dmitri , Miani Andrea , Halonen Lauri
Published: July 2002

Laser-induced fluorescence has been used to investigate overtone states of water. Specific rovibrational states have been excited by a high-resolution Titanium:sapphire ring laser in the near-infrared region. The resulting fluorescence light around 3000–4000 cm−1 has been dispersed by a Fourier transformation interferometer. Rich collision-induced spectra are obtained. The specific nuclear spin states chosen by the laser excitation are conserved in collisional processes. Interesting vibrational intensity effects have been observed. Vibrational calculations with an exact kinetic energy operator in the curvilinear internal coordinate representation have been performed to compute emission intensities.
Local density augmentation in attractive supercritical solutions. II. Application to electronic line shifts
Authors: Egorov S. A.
Published: July 2002

A microscopic statistical mechanical theory of electronic solvatochromism in supercritical fluids is presented. A microscopic expression for the solvent-induced electronic line shift is given, which involves the solute–solvent radial distribution function and interaction potentials. The radial distribution function is obtained from the integral equation theory of inhomogeneous fluids. The theory is applied to study the experimentally observed nonlinear density dependence of spectral line shifts in supercritical fluids in the near critical region. Model calculations of spectral shifts are performed for a range of solvent densities and temperatures and model potential parameters. In addition, a quantitative comparison of the theory with experimental data on electronic line shifts is performed, and the agreement is satisfactory.
Killing spinors and gravitational perturbations
Authors: Torres del Castillo G. F.
Published: July 2002

It is shown that in a vacuum space-time, possibly with a nonzero cosmological constant, which admits a D(1,0) Killing spinor, one component of the perturbed Weyl spinor that satisfies a decoupled equation, when multiplied by an appropriate factor made out of the components of the Killing spinor, constitutes a Debye potential that generates metric perturbations of the considered background. It is also shown that in the case where the background is of type N, there is an operation that relates the gravitational perturbations and the zero-rest-mass fields of spin-0, - 1/2 , and -1.
On the two-point functions of interacting Wightman fields
Authors: Baumann Klaus
Published: July 2002

Let A be a relativistic local field. If its two-point function in momentum space W̃2( p) has a falloff such that for some α>0, W̃2( p)eα( p2)1/2 is still a tempered distribution, then A is necessarily a generalized free field.
Pure Lie algebraic approach to the modified Korteweg–de Vries equation
Authors: Post G.
Published: July 2002

It is explained, using only Lie algebraic means, how the modified-KdV-like equations arise. As an example, the modified-KdV equation is treated.
Path integral for second-derivative Lagrangian L=(κ/2)ẍ2+(m/2)ẋ2+(k/2)x2−j(τ)x(τ)
Authors: Kleinert H.
Published: July 2002

For the above second-derivative Euclidean Lagrangian, the quantum statistical probability distribution (xbvbτb‖ xavaτa) that an orbit x(τ) with initial position xa and velocity ẋa=va arrives at a final point xb and velocity ẋb=vb is calculated.
On subalgebras of the Lie algebra of the extended Poincaré group P̃(1,n)
Authors: Barannik L. F. , Fushchich W. I.
Published: July 2002

Some general results on the subalgebras of the Lie algebra AP̃(1,n) of the extended Poincaré group P̃(1,n) (n≥2) with respect to P̃(1,n) conjugation have been obtained. All subalgebras of AP̃(1,4) that are nonconjugate to the subalgebras of AP(1,4) are classified with respect to P̃(1,4) conjugation. The list of representatives of each conjugacy class is presented.
The many-component limit of the Potts lattice gauge model in the external field
Authors: Maślanka Pawel/
Published: July 2002

This paper generalizes the results obtained by Kotecky. The free energy of the gauge Potts model in the external field in the many component limit has been calculated. This is done in two cases: (a) the external field is switched on after the gauge fixing or (b) the external field is switched on before the gauge fixing. In both cases, the free energy can be calculated using the mean-field method, if, in case (b), the larger class of trial measures is allowed. The mechanism of phase transition is also discussed.
On relativistic irreducible quantum fields fulfilling CCR
Authors: Baumann Klaus
Published: July 2002

Let φ be a relativistic scalar field fulfilling canonical commutation relations (CCR). Furthermore it is assumed that the time zero fields and momenta form an irreducible set. Based on estimates given by Herbst [I. W. Herbst, J. Math. Phys. 17, 1210 (1976)], and by methods developed by Powers [R. T. Powers, Commun. Math. Phys. 4, 145 (1967)], it is shown that φ has to be a free field in n>3 space dimensions. For n=3 (resp. n=2) restrictions that look similar to the restriction in a formal :φ4:3+1 (resp. :φ6:2+1) theory are obtained.
Analytical continuation of the Faddeev equation for local potentials
Authors: Delfino A.
Published: July 2002

It is shown how to analytically continue the Faddeev equation in the second sheet of the complex energy plane when one has a local two-body interaction.
Nontrivial zeros of the Wigner (3j ) and Racah (6j ) coefficients. II. Some nonlinear solutions
Authors: Brudno Simcha
Published: July 2002

Additional formulas for nontrivial zeros in the 3j and 6j symbols have been found for some higher-order cases, i.e., where k=2, 3, and 4 (numerical examples only).
The Teukolsky–Starobinsky identities in type D vacuum backgrounds with cosmological constant
Authors: Torres del Castillo G. F.
Published: July 2002

It is shown that in all the type D solutions to the Einstein vacuum field equations with cosmological constant, the one-variable functions appearing in the separable maximal spin-weight components of the neutrino, electromagnetic, and gravitational perturbations are related by certain differential operators and the corresponding proportionality constants are obtained. It is also shown that analogous relations hold in the case of perturbations by a Rarita–Schwinger field if the cosmological constant vanishes.
Symmetries of Einstein’s field equations with a perfect fluid source as examples of Lie–Bäcklund symmetries
Authors: Stephani H.
Published: July 2002

The framework of Lie–Bäcklund (or generalized) symmetries is used to give a unifying view of some of the known symmetries of Einstein’s field equations for the vacuum or perfect fluid case (with a μ=p or a μ+3p=0 equation of state). These symmetries occur if space-time admits one or two Killing vectors (orthogonal or parallel, respectively, to the four-velocity in the perfect fluid case).
A remark on BRST quantization
Authors: Thomi P.
Published: July 2002

Using rigged Hilbert space techniques, the scalar product on the BRST cohomology for certain bosonic systems is rigorously defined.
Periodic reduction of self-dual Yang–Mills equations
Authors: Nakamura Yoshimasa
Published: July 2002

A class of GL(∞)-invariant self-dual Yang–Mills (SDYM) equations is considered. It is shown that the GL(∞) SDYM equations are reduced to the GL(n,C) SDYM hierarchy by imposing a periodic condition. This reduction procedure makes clear a relationship between our GL(∞) SDYM equations and the usual infinite matrix representation of a single GL(n,C) SDYM equation.
Electromagnetic scattering for a class of anisotropic layered media
Authors: Roberts Thomas M. , Sabbagh Harold A. , Sabbagh L. David
Published: July 2002

The problem of computing fields produced by currents in the presence of unflawed layered media is reduced to quadrature. Each layer either has single-axis-type anisotropy or is isotropic. Integral equations are derived for fields in the presence of layered media with flaws.
Theory of fluctuations and small oscillations for quantum lattice systems
Authors: Goderis D. , Verbeure A. , Vets P.
Published: July 2002

The theory of fluctuations for a quantum lattice system is rigorously defined. The property of stability of equilibrium states against macroscopic fluctuations is formulated and small oscillations around equilibrium are studied.
Padé oscillators and a new formulation of perturbation theory
Authors: Znojil M.
Published: July 2002

Being guided by the problem of bound states in potentials close to their Padé approximants, a new Rayleigh–Schrödinger-type perturbation theory is developed. The unperturbed system is understood: here in a broader sense: its solutions are not needed, but merely the related nondiagonal unperturbed propagator R. In particular, all the chain models H0ψ=ES0ψ (H0, S0=band matrices) with arbitrary perturbations are then perturbatively solvable, with R constructed in terms of auxiliary matrix continued fraction fn. Alternatively, a ‘‘generalized unperturbed spectrum’’ f̂n may be required as an input: The algebraically constructed asymptotics of the fn’s play this role in our Padé examples. Due to S≠I, the‘‘Sturmians’’ may also be constructed. In the test evaluations of the binding energies and/or couplings, the simultaneous upper and lower bounds of high precision are shown to be numerically obtainable.
The exterior metric approach to a charged axially symmetric celestial body—the fourth-order approximate solutions of Einstein–Maxwell equations
Authors: Qi-huang Zhou
Published: July 2002

Starting with the general expression of a static state axisymmetric metric and using the principle of equivalence and the Maccullagh formula, the Einstein–Maxwell equations of a charged axisymmetric celestial body are obtained. Next, using the method of undetermined coefficients these equations are solved up to fourth-order approximate. These sets of solutions are generally appropriate for all kinds of charged axisymmetric celestial bodies.
n
k
almost-tangent structures and the Hamiltonization of higher-order field theories
Authors: de León Manuel , Rodrigues Paulo R.
Published: July 2002

In this paper a new interpretation of the Hamiltonization of higher-order Lagrangian field theories is given, introducing a new class of tensor fields of type (1, 1) that extends almost-tangent structures to the tangent bundle of nk velocities.
The hidden variable problem in algebraic relativistic quantum field theory
Authors: Rédei Miklós
Published: July 2002

Given two quasilocal C*-algebras A and B of relativistic quantum field theory, their state spaces E(A) and E(B), and a positive, unit preserving map L: B→A respecting the relativistic quasilocal structure of A and B, (B,E(B)) is said to be a local hidden theory of (A,E(A)) via L if for every state φ in E(A) the state L*φ∈E(B) can be decomposed in E(B) via a subcentral measure into states with pointwise strictly less dispersion than the dispersion of φ. It is shown that if there is a unique, locally normal, locally faithful, analytic vacuum state in E(A) then (A,E(A)) cannot have a local hidden theory (B,E(B)) via L. This improves the result obtained in J. Math. Phys. 28, 833 (1987).
The algebraical structure of the electromagnetic tensor and description of charged particles moving in the strong electromagnetic field
Authors: Rylov Yu. A.
Published: July 2002

In the event space the electromagnetic tensor eigenvectors generate two sets of invariant baselines, which are tangent to these eigenvectors. In the case of a slowly changing electromagnetic field the charged particles are shown to move along a helix around these baselines (the guiding center approximation). In the case of strong radiation damping (a strong field and a small mass) the helical motion of the particle transforms into the motion along the baseline (the massless approximation). In the self-consistent electromagnetic field the gas of charged massless particles can contain two-phase regions (the capture regions). Inside the capture regions the gas can consist of two phases: (1) a dynamical phase (DP) moving with the speed of light, and (2) a statical phase (SP) moving with speed less than that of light. An understanding of the two-phase character of the ultrarelativistic electron–positron gas is very important for investigation of magnetosphere processes in pulsars.
Character formulas for irreducible modules of the Lie superalgebras sl(m/n)
Authors: Van der Jeugt J. , Hughes J. W. B. , King R. C. , Thierry-Mieg J.
Published: July 2002

Kac distinguished between typical and atypical finite-dimensional irreducible representations of the Lie superalgebras sl(m/n) and provided an explicit character formula appropriate to all the typical representations. Here, the range of validity of some character formulas for atypical representations that have been proposed are discussed. Several of them are of the Kac–Weyl type, but then it is proved that all formulas of this type fail to correctly give the character of one particular atypical representation of sl(3/4). Having ruled out, therefore, all such formulas, a completely new extension of the Kac–Weyl character formula is proposed. The validity of this formula in the case of all covariant tensor irreducible representations is proved, and some evidence in support of the conjecture that it covers all irreducible representations of sl(m/n) is presented.
The trivialization of constraints in quantum theory (working in a general gauge/parametrization)
Authors: Shiekh A. Y.
Published: July 2002

A way is found to trivialize and so deal with constraints in a gauge invariant manner.
Global aspects of light cone cuts
Authors: Kozameh Carlos , Lamberti Pedro W. , Reula Oscar
Published: July 2002

The global behavior of light cone cuts at null infinity, i.e., the intersection of light cones of interior point, with null infinity, is investigated. In particular, it is shown that the topological structure of these cuts, for the case of an asymptotically flat space-time, is very simple. The nature of the light cone cuts singularities is also analyzed. Generically, only two different types of singularities occur and their local description is given.
Quantum aspects of Bellert’s theory
Authors: Rydzyńska Ewa
Published: July 2002

It is proved that Bellert’s cosmological theory (with its mathematical apparatus) gives the same values of expectations of physical quantities as quantum mechanics. It is also shown that one of the uncertainty principles, fundamental in relativity quantum mechanics, holds in Bellert’s theory, too. Thanks to this fact, an approximation of the length of the quantum of time in Bellert’s theory is obtained.
Representations of quantum matrix algebra M
q(2) and its q-boson realization
Authors: Ge Mo-Lin , Liu Xu-Feng , Sun Chang-Pu
Published: July 2002

In this paper it is proved that the nontrivial finite-dimensional irreducible representations of the quantum matrix algebra Mq(2) [or the coordinate ring of the quantum group GLq(2)] exist only when q is a root of unity, and thereby construct such representations for Mq(2). Some finite-dimensional indecomposable representations of Mq(2) are also explicitly presented. Finally, the q-boson realization of Mq(2) is discussed, and it is shown that it works in this case as well as in the quantum algebra case.
Quantum spectra of zero modes, topological vacua and dynamical supersymmetry breaking in non-abelian gauge theories
Authors: Zhang H.
Published: July 2002

Some aspects of supersymmetric gauge theories are discussed intimately connected to the Lie algebras of the gauge groups. From the discussions of zero modes in non-abelian gauge theories, a formula for the quantum spectra of the classical zero modes in supersymmetric gauge theories is obtained. Some relevant aspect of topological vacua in higher dimensions are also discussed. As a physics application, the spectrum formula and the discussions of the topological vacua are applied to the determinations of dynamical supersymmetry breaking. Especially, for gauge theories without gauge symmetry breaking in quantum dynamics, dynamical supersymmetry breaking does not occur in supersymmetric non-abelian gauge theories in D=4 and higher dimensions for any value of the gauge coupling constant and independent of the vacuum angle in the theories if the theory is asymptotically free.
Exact and avoided crossings of adiabatic hyperspherical potential curves
Authors: Kostrykin Vadim V. , Kvitsinsky Andrei A.
Published: July 2002

Exact crossing of potential curves related to the adiabatic hyperspherical (AH) approach to a three-body Coulomb system is studied. Analytic structure of the AH potential curves, harmonics, and coupling matrix elements near crossing points in the complex plane of hyperradius is investigated. Results are applied to derive some basic features of avoided crossings of the AH potential curves at real hyperradii.
Geodesic multiplication and the theory of gravity
Authors: Kuusk Piret , Örd Jüri , Paal Eugen
Published: July 2002

Nonassociative algebraic systems called local geodesic loops and their tangent Akivis algebras are considered. The construction of geo-odular structure of a manifold with an affine connection is briefly reviewed. A possible role of these algebraic structures in classical and quantum gravity is discussed.
Random time evolution and direct integrals: Constants of the motion and the mass operator
Authors: Tip A.
Published: July 2002

The members Hω=p2+Vω(x) of ergodic families of random operators, defined in ℋ=L2(Rd), are considered as acting in fibers in a direct integral decomposition of 𝒦=L2(Ω,P(dω);ℋ), (Ω,P) being the underlying probability space. Such a formulation may turn out to be useful in providing a rigorous background for theoretical physical methods employed in treating random systems. As an example a rigorous definition of the mass operator Σ(z) is presented and the formulation of transport equations in a functional analytic setting is briefly indicated. In case there is translational invariance in the probability law the operator H is shown to be unitarily equivalent to an operator Ĥ, which can be decomposed, Ĥ→Ĥ(k), in a way that diagonalizes p. Thus problems about averaged time evolution can be formulated entirely in terms of Ĥ(k) in L2(Ω,P).
Reduction of space–time by a constraint for C(0) metrics
Authors: Hortaçsu M. , Özdemir N.
Published: July 2002

It is shown how a constraint imposed by the physical relevance of the solutions reduces the dimension of space–time. The C(0) metric given by Nutku is used to describe gravitational shock waves and the trivial case is looked at. It is found that imposing triviality on the solutions reduces the dimension of space–time by one.
A construction of transitively differential groups of degree 3
Authors: Kantor I. L. , Patera J.
Published: July 2002

Some general results on Lie algebras of first order differential operators in n real variables with polynomial (degree ≤3) coefficients are demonstrated. An infinite family of specific Lie algebras and the corresponding Lie groups are described.
Wavelets and the Poincaré half-plane
Authors: Klauder J. R. , Streater R. F.
Published: July 2002

A square-integrable signal of positive energy is transformed into an analytic function in the upper half-plane, on which SL(2,R) acts. It is shown that this analytic function is determined by its scalar products with the discrete family of functions obtained by acting with SL(2,Z) on a cyclic vector, provided that the spin of the representation is less than 3.
Symmetries of the Ablowitz–Kaup–Newell–Segur hierarchy
Authors: Kiso Kazuhiro
Published: July 2002

Nonlocal symmetries of the Ablowitz–Kaup–Newell–Segur (AKNS) hierarchy are introduced and it is shown that the symmetry algebra of the AKNS hierarchy is isomorphic to the loop algebra sl(2,C)⊗C[λ, λ−1]. As a special case, the symmetry algebra of the nonlinear Schrödinger equation is determined and is shown to be isomorphic to the loop algebra su(2)⊗R[λ, λ−1] or g⊗R[λ, λ−1] corresponding to the sign of the nonlinear term, where g is a noncompact real form of sl(2,C).
Quantum canonical transformations revisited
Authors: Shiekh A. Y.
Published: July 2002

A preferred form for the path integral discretization is suggested that allows the implementation of canonical transformations in quantum theory.