Search

The use of the mixed reference (MR) reduced density matrix, which combines reduced density matrices of the MS = +1 and -1 triplet-ground states, is proposed in the context of the collinear spin-fliptime-dependent density functional theory (SF-TDDFT) methodology. The time-dependent Kohn-Sham equation with the mixed state is solved by the use of spinor-like open-shell orbitals within the linear response formalism, which enables to generate additional configurations in the realm of TD-DFT. The resulting MR-SF-TDDFT computational scheme has several advantages before the conventional collinear SF-TDDFT. The spin-contamination of the response states of SF-TDDFT is nearly removed. This considerably simplifies the identification of the excited states, especially in the "black-box" type applications, such as the automatic geometry optimization, reaction path following, or molecular dynamics simulations. With the new methodology, the accuracy of the description of the excited states is improved as compared to the collinear SF-TDDFT. Several test examples, which include systems typified by strong non-dynamic correlation, orbital (near) degeneracy, and conical intersections, are given to illustrate the performance of the new method. [ABSTRACT FROM AUTHOR]

Orbital-optimized second-order perturbation theory (OOMP2) optimizes the zeroth order wave function in the presence of correlations, removing the dependence of the method on Hartree-Fock orbitals. This is particularly important for systems where mean field orbitals spin contaminate to artificially lower the zeroth order energy such as open shell molecules, highly conjugated systems, and organometallic compounds. Unfortunately, the promise of OOMP2 is hampered by the possibility of solutions being drawn into divergences, which can occur during the optimization procedure if HOMO and LUMO energies approach degeneracy. In this work, we regularize these divergences through the simple addition of a level shift parameter to the denominator of the MP2 amplitudes. We find that a large level shift parameter of 400 mEh removes divergent behavior while also improving the overall accuracy of the method for atomization energies, barrier heights, intermolecular interactions, radical stabilization energies, and metal binding energies. [ABSTRACT FROM AUTHOR]

At oil refineries, furnaces account for much of the energy expenditure. Energy efficiency may be improved by means of an integrated system that contains a furnace and a unit for heating the incoming gas with energy recovered from the smokestack gases. By exergetic analysis and efficiency assessment of the energy distribution in the system (on the basis of the zeroth law of thermodynamics), a multifunctional approach to effective integration of the furnace subsystem and the energy subsystem is proposed. That results in greater stability of the integrated system; provides the energy required for all the technological operations, as well as additional inexpensive electrical power; and helps curb thermal pollution of the environment. This approach may be adopted in modernizing existing systems or creating new systems. [ABSTRACT FROM AUTHOR]

What is now known as the zeroth 'law' of thermodynamics was first stated by Maxwell in 1872: at equilibrium, 'Bodies whose temperatures are equal to that of the same body have themselves equal temperatures.' In the present paper, we give an explicit mathematical proof of the zeroth 'law' for classical, deterministic, T-mixing systems. We show that if a body is initially not isothermal it will in the course of time (subject to some simple conditions) relax to isothermal equilibrium where all parts of the system will have the same temperature in accord with the zeroth 'law.' As part of the derivation we give for the first time, an exact expression for the far from equilibrium thermal conductivity. We also give a general proof that the infinite-time integral, of transient and equilibrium autocorrelation functions of fluxes of non-conserved quantities vanish. This constitutes a proof of what was called the 'heat death of the Universe' as was widely discussed in the latter half of the 19th century. [ABSTRACT FROM AUTHOR]

A cusp correction scheme for the relativistic zeroth-order regular approximation (ZORA) quantum Monte Carlo method is proposed by extending the nonrelativistic cusp correction scheme of Ma et al. [J. Chem. Phys. 122, 224322 (2005)]. In this scheme, molecular orbitals that appear in Slater–Jastrow type wave functions are replaced with the exponential-type correction functions within a correction radius. Analysis of the behavior of the ZORA local energy in electron-nucleus collisions reveals that the Kato’s cusp condition is not applicable to the ZORA QMC method. The divergence of the electron-nucleus Coulomb potential term in the ZORA local energy is remedied by adding a new logarithmic correction term. This method is shown to be useful for improving the numerical stability of the ZORA-QMC calculations using both Gaussian and Slater basis functions. [ABSTRACT FROM AUTHOR]

Complete active space self-consistent field (CASSCF) calculations and subsequent second-order perturbative treatment (CASPT2) have been carried out on a series of metallic complexes based on a Fe(II)N6 core. These compounds play a determinant role in the elaboration of potential bistable architectures such as spin-crossover materials. The adiabatic energies between the high-spin (HS) (S=2) and low-spin (LS) (S=0) states are evaluated with respect to the value of the shift ionization potential–electronic affinity (IPEA shift) recently introduced in the zeroth-order Hamiltonian [Ghigo et al., Chem. Phys. Lett. 396, 142 (2004)]. Based upon a series of experimental data, it is concluded that the commonly applied IPEA shift value (0.25 a.u.) is not satisfactory to properly discriminate the open-shell HS and closed-shell LS states. We suggest that a 0.50–0.70 a.u. value would be preferable for these specific adiabatic gap calculations. [ABSTRACT FROM AUTHOR]

In this work we calculate the photoelectron spectra of the PtX42- (X=F,Cl,Br) dianions by application of the third-order Dirac–Hartree–Fock one-particle propagator technique. Relativistic effects and electron correlation are hereby treated on a consistent theoretical basis, which is mandatory for systems containing heavy elements. An experimental PtF42- gas phase photoelectron (PE) spectrum is not available and our calculations confirm its instability against autodetachment. For PtCl42- potential curves for the two Jahn–Teller (JT), active modes were determined and the influence of spin-orbit splitting on the JT stabilization is discussed. The scalar relativistic and four-component potential energy curves hereby exhibit remarkable differences relevant for the correct interpretation of the spectra. A dissociation channel through the b2g vibrational mode was obtained for PtCl42- in the 2Eu final state. For all species electron correlation strongly decreases the ionization potentials and the inclusion of spin-orbit coupling leads to alterations in the level order, which have to be taken into account for a correct peak assignment. The metal d contribution to the valence orbitals steadily decreases from the PtF42- to the PtBr42- compound, which rules out a pure metal d-orbital-based interpretation of the valence PE spectrum. [ABSTRACT FROM AUTHOR]

Short period superlattices of AlN/Al0.08Ga0.92N with the average AlN content over 60% have been investigated by high resolution x-ray diffraction. The a and c lattice constants verify these structures to be strain relaxed. Monolayer-level interface roughness, caused by the presence of threading dislocations and step-flow growth mode, is simulated and directly compared with the zeroth and ±1 satellite peak positions of the rocking curves. It was found that the observed x-ray diffraction data can be adequately described by considering primarily the presence of screw dislocations and step-flow growth mode. [ABSTRACT FROM AUTHOR]

The linear response within the elimination of the small component formalism is aimed at obtaining the leading order relativistic corrections to magnetic molecular properties in the context of the elimination of the small component approximation. In the present work we extend the method in order to include two-body effects in the form of a mean field one-body operator. To this end we consider the four-component Dirac-Hartree-Fock operator as the starting point in the evaluation of the second order relativistic expression of magnetic properties. The approach thus obtained is the fully consistent leading order approximation of the random phase approximation four-component formalism. The mean field effect on the relativistic corrections to both the diamagnetic and paramagnetic terms of magnetic properties taking into account both the Coulomb and Breit two-body interactions is considered. [ABSTRACT FROM AUTHOR]

Generalized thermodynamics or extended irreversible thermodynamics presumes the existence of thermodynamic intensive variables (e.g., temperature, pressure, chemical potentials, generalized potentials) even if the system is removed from equilibrium. It is necessary to properly understand the nature of such intensive variables and, in particular, of their fluctuations, that is, their deviations from those defined in the extended irreversible thermodynamic sense. The meaning of temperature is examined by means of a kinetic theory of macroscopic irreversible processes to assess the validity of the generalized (or extended) thermodynamic method applied to nonequilibrium phenomena. The Boltzmann equation is used for the purpose. Since the relative Boltzmann entropy has been known to be intimately related to the evolution of the aforementioned fluctuations in the intensive thermodynamic variables, we derive the evolution equations for such fluctuations of intensive variables to lay the foundation for investigating the physical implications and evolution of the relative Boltzmann entropy, so that the range of validity of the thermodynamic theory of irreversible processes can be elucidated. Within the framework of this work, we examine a special case of the evolution equations for the aforementioned fluctuations of intensive variables, which also facilitate investigation of the molecular theory meaning of the zeroth law of thermodynamics. We derive an evolution equation describing the relaxation of temperature fluctuations from its local value and present a formula for the temperature relaxation time. [ABSTRACT FROM AUTHOR]

Without invoking the Markov approximation, we derive formulas for vibrational energy relaxation (VER) and dephasing for an anharmonic system oscillator using a time-dependent perturbation theory. The system-bath Hamiltonian contains more than the third order coupling terms since we take a normal mode picture as a zeroth order approximation. When we invoke the Markov approximation, our theory reduces to the Maradudin-Fein formula which is used to describe the VER properties of glass and proteins. When the system anharmonicity and the renormalization effect due to the environment vanishes, our formulas reduce to those derived by and Mikami and Okazaki [J. Chem. Phys. 121, 10052 (2004)] invoking the path-integral influence functional method with the second order cumulant expansion. We apply our formulas to VER of the amide I mode of a small amino-acid like molecule, N-methylacetamide, in heavy water. [ABSTRACT FROM AUTHOR]

We propose a zeroth-order Hamiltonian for many-body perturbation theory based on the unitary decomposition of the two-particle reduced Hamiltonian. For the zeroth-order Hamiltonian constrained to be diagonal in the Hartree–Fock basis set, the two-particle reduced perturbation matrix is chosen to have a minimal Frobenius norm. When compared with the Mo\ller–Plesset partitioning, the method yields more accurate second-order energies. [ABSTRACT FROM AUTHOR]

We present a method for improving the accuracy and efficiency of interpolation methods, in which an analytical zeroth-order potential-energy surface is employed as a reference surface. To investigate and test the method, we apply it to hydrogen peroxide where there exists an accurate analytical surface which we take as the “exact” surface for obtaining the energies and derivatives for fitting and assessing the accuracy. Examples are given for four-dimensional and six-dimensional surfaces interpolated by using either the modified Shepard or second-degree interpolating moving least-squares approach, with comparisons for cases with and without using the zeroth-order potential. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Scale-invariant fluxes are the defining property of turbulent cascades, but their direct measurement is a challenging experimental problem. Here we perform such a measurement for a direct energy cascade in a turbulent quantum gas. Using a time-periodic force, we inject energy at a large length scale and generate a cascade in a uniformly trapped three-dimensional Bose gas. The adjustable trap depth provides a high-momentum cutoff kD, which realizes a synthetic dissipation scale. This gives us direct access to the particle flux across a momentum shell of radius kD, and the tunability of kD allows for a clear demonstration of the zeroth law of turbulence. Moreover, our time-resolved measurements give unique access to the pre–steady-state dynamics, when the cascade front propagates in momentum space. [ABSTRACT FROM AUTHOR]

The permanent magnet synchronous motors (PMSMs) with space vector pulsewidth modulation (SVPWM) technique will inevitably introduce sideband current harmonic components around the carrier frequency. The armature reaction field caused by the sideband current interacts with the permanent magnet field, generating sideband electromagnetic force and resulting in high-frequency noise. This paper provides a comparative study of the sideband electromagnetic force in internal and external rotor PMSMs with SVPWM technique. First, the analytical model of the electromagnetic force in internal and external rotor PMSMs is established based on the Maxwell tensor method. The source, spatial order, and frequency of the electromagnetic force is obtained. Then, the spatial and temporal characteristics of the sideband force in internal and external rotor PMSMs with different pole and slot combinations are derived and investigated. The results show that the frequency characteristics of the zeroth order sideband force in internal and external rotor PMSMs introduced by SVPWM are identical. However, the frequency characteristics demonstrate significant differences for the nonzeroth order sideband force. Finally, the theoretical analysis is validated through the finite element and experimental results, respectively. This study is benefit for the source identification and reduction of high-frequency acoustic noise for PMSMs. [ABSTRACT FROM AUTHOR]

Abstract The Defect Recollement, Restriction Recollement, Auslander–Gruson–Jensen Recollement, and others, are shown to be instances of a general construction using zeroth derived functors and methods from stable module theory. The right derived functors W k : = R k ( _) ⁎ are computed and it is shown that the functor W 2 : = R 2 ( _) ⁎ is right exact and restricts to a duality W of the defect zero functors. The duality W satisfies two identities which we call the Generalised Auslander–Reiten formulas. We show that W induces the generalised Auslander–Bridger transpose and show that the Generalised Auslander–Reiten formulas reduce to the well-known Auslander–Reiten formulas. [ABSTRACT FROM AUTHOR]

Azimuthal surface waves are eigenmodes of cylindrical plasma–dielectric–metal structures both in the presence of and without an axial static magnetic field. They are actively studied due to possible applications in plasma electronics, nanotechnologies and biomedical diagnostics. Higher radial modes are known to propagate at higher frequencies and shorter wavelengths compared to those of the zeroth mode, a feature which is of interest for practical applications. To gain the advantage of the excitation of higher radial modes of azimuthal surface waves one has first to know their dispersion properties. This paper generalizes the results of earlier papers by including a static axial magnetic field and considering the higher radial modes. The presence of the constant axial magnetic field removes the degeneracy in the wave spectrum with respect to the sign of the azimuthal wavenumber. [ABSTRACT FROM AUTHOR]

In this study, we introduce a relativistic quantum mechanical wave equation of the spin-1 particle as an excited state of the zitterbewegung and show that it is consistent with the 2 + 1 dimensional Proca theory. At the same time, we see that in the rest frame, this equation has two eigenstates; particle and antiparticle states or negative and positive energy eigenstates, respectively, and satisfy SO(2,1) spin algebra. As practical applications, we derive the exact solutions of the equation in the presence of a constant magnetic field and a curved spacetime background. From these solutions, we find Noether charge by integrating the zeroth component of the spin-1 particle current, called charge density, on hyper surface and discuss pair production from this charge. And, we see that the discussion on the Noether charge is a useful tool for understanding the pair production phenomenon because it is derived from a probabilistic particle current. [ABSTRACT FROM AUTHOR]

In this paper, a calibration method is proposed which eliminates the zeroth order effect in lateral shearing interferometry. An analytical expression of the calibration error function is deduced, and the relationship between the phase-restoration error and calibration error is established. The analytical results show that the phase-restoration error introduced by the calibration error is proportional to the phase shifting error and zeroth order effect. The calibration method is verified using simulations and experiments. The simulation results show that the phase-restoration error is approximately proportional to the phase shift error and zeroth order effect, when the phase shifting error is less than 2° and the zeroth order effect is less than 0.2. The experimental result shows that compared with the conventional method with 9-frame interferograms, the calibration method with 5-frame interferograms achieves nearly the same restoration accuracy. [ABSTRACT FROM AUTHOR]

In this paper, a compact coplanar waveguide (CPW) based dual-band bandpass filter has been proposed. The modified complementary split ring resonator (CSRR) structure at CPW ground plane is investigated for designing of dual-band bandpass filter with minimum insertion loss. The zeroth order resonance (ZOR) frequency depends on shunt parameter due to open ended boundary condition. The dual-band bandpass filter with return loss 21 and 20 dB, insertion loss 0.5 and 0.4 dB at 1.8 and 3.2 GHz, respectively, are simulated and measured. The measured 3 dB fractional bandwidths are 92.7% and 18.8% with respect to their centre frequencies of passbands. The simulated and measured results are showing good agreement in the passband. The electrical size of designed filter is 0.10 λ 0  × 0.09 λ 0  × 0.007 λ 0 , where λ 0 is the free space wavelength at the resonance frequency of first pass band. It is suitable for a global system for mobile (GSM) and long term evolution (LTE) in different service bands of 900, 1800, 1900 and 2300 MHz wireless communication applications. [ABSTRACT FROM AUTHOR]

A Monte Carlo method implemented in the PRIZMA-DSP code to calculate multiplying systems, including weakly coupled systems, is described. In the code, the basis of the method is a sequential calculation of a prescribed chain of active generations, which is described by, first and foremost, the dominant ratio of the system. The fission points of the running generation serve as a source for constructing neutron trajectories, new fission points arising on a trajectory are transmitted unchanged to calculate the next generation, and so on. In the calculation of the active generation, Keff and made-to-order linear-fractional functions are evaluated. In order for the distribution to become established, a passive calculation with prescribed chain length is made before the active calculation. In addition, after the calculation of each generation the operation of random mixing of the entire set of fission points and their distribution over the nuclei is performed in order to obtain a uniform distribution. At the start of the calculation, a special rejection procedure performs a pre-set number of preliminary computational iterations so that an arbitrary zeroth distribution over all nuclei goes to a distribution obtained via a characteristic function. [ABSTRACT FROM AUTHOR]

Input-output partial feedback linearisation is demonstrated experimentally for the first time on a system with non-smooth nonlinearity, a laboratory three degrees of freedom lumped mass system with a piecewise-linear spring. The output degree of freedom is located away from the nonlinearity so that the partial feedback linearisation possesses nonlinear internal dynamics. The dynamic behaviour of the linearised part is specified by eigenvalue assignment and an investigation of the zero dynamics is carried out to confirm stability of the overall system. A tuned numerical model is developed for use in the controller and to produce numerical outputs for comparison with experimental closed-loop results. A new limitation of the feedback linearisation method is discovered in the case of lumped mass systems – that the input and output must share the same degrees of freedom. [ABSTRACT FROM AUTHOR]

This paper presents design and analysis of a novel configuration of the zeroth order coplanar waveguide (CPW) resonator (ZOR). It is based on composite right/left-handed transmission line (CRLH-TL) metamaterial unit cell, it provides size reduction, extended bandwidth and better efficiency. The realized antenna has a compact size of (0.183λ0× 0.183λ0× 0.027λ0) at 5.5 GHz, and gives high flexibility in the design, due to the fact that metamaterial resonant antenna is printed on a single layer CPW, without using vias. The bandwidth, directivity and radiation efficiency of the proposed antenna is about 123.3%, 0.65 dB and 76% at 5.5GHz, respectively. Its bandwidth is improved compared with the other ZOR antennas. The antenna was designed to operate from 4.55 to 11.33 GHz and possesses a reflection coefficient of -23.7 dB at the zeroth order resonance frequency. The proposed antenna (1-cell ZOR) achieves a 61.5 % reduction in patch size compared to a conventional half-wavelength patch antenna at the frequency 5.5GHz. The proposed ZOR antenna are also very compact in size and has a via-free coplanar structure. Therefore, making the proposed antenna suitable for use in wireless hand-held devices. [ABSTRACT FROM AUTHOR]

This paper describes the problem of determining the temperature of laminar gas flow, in which the equation of convective heat transfer contains two variable coefficients, is reduced to nonclassical problems for zeroth and first asymptotic expansion coefficient with respect to a formal parameter. The Laplace-Carson transform are used to obtain analytical expressions for the temperature field of ascending laminar gas flow in a well with account for the relationships of density and velocity with spatial coordinates in zeroth and first asymptotic approximations. Expressions for the temperature asymptotically averaged along the cross section of the well and temperature distributions over the cross-sectional radius are obtained. [ABSTRACT FROM AUTHOR]

In a recent paper on radiation pressure forces exerted on a homogenous spherical particle by zeroth-order Mathieu beams (zMBs), the integral localized approximation(ILA) was used to calculate the beam shape coefficients (BSCs) encoding the shape of the beams. Unfortunately, this method is valid only for beams with a propagating factor exp ( ± ikz ). In the case of non-diffracting beams the propagation factor is exp (± ik cos α  z ) which involves an extra-cosine term, with α being the axicon angle. Due to this term it has been demonstrated that localized approximations, including ILA, provide a satisfactory description of the intended beam only if the axicon angle is small enough. Zeroth-order Mathieu beams pertain to this type of beams. The present paper is therefore devoted to a comparison between BSCs calculated with an exact procedure and those calculated using ILA, in order to determine a range of validity of the approximate procedure. As a side result, we also establish exact closed-form expressions to the evaluation of BSCs of zMBs. [ABSTRACT FROM AUTHOR]

Motivated by black holes thermodynamics, we consider the zeroth law of thermodynamics for systems whose entropy is a quasi-homogeneous function of the extensive variables. We show that the generalized Gibbs–Duhem identity and the Maxwell construction for phase coexistence based on the standard zeroth law are incompatible in this case. We argue that the generalized Gibbs–Duhem identity suggests a revision of the zeroth law which in turns permits to reconsider Maxwell's construction in analogy with the standard case. The physical feasibility of our proposal is considered in the particular case of black holes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of College of Education is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on the Euclidean approach, we consider the effects of quantum gravity and mass-less matter on the thermodynamic properties of Schwarzschild black hole. The techniques of effective field theory are utilized to analytically construct the partition function at the one-loop level. Using the non-local heat kernel formalism, the partition function is expressed as a curvature expansion. We extensively discuss the effect of the corrections on the thermodynamic stability. The one-loop free energy shows, remarkably, that a large number of gauge fields is able to render Schwarzschild black hole thermodynamically stable. The black hole mass at which stability is achieved scales as $$ \sqrt{N} $$ in Planck units, where N is the number of gauge fields, and is independent of any UV completion of quantum gravity. [ABSTRACT FROM AUTHOR]

A general framework is presented based on the least squares polynomial regression to design time filters for the leapfrog time-stepping scheme with required amplitude and phase properties. The well-known Robert-Asselin filter and its modification, the Robert-Asselin-Williams filter, are obtained using the zeroth-degree and first-degree polynomial regression, respectively. It is shown that using the second-degree polynomial regression, one can achieve seventh-order amplitude accuracy with only four time levels. In addition, the designed filter exhibits promising results when used with a semi-implicit time-stepping scheme. [ABSTRACT FROM AUTHOR]

For components with different defects, selecting a proper criterion to predict their failure is very important, hut sometimes this brings confusion to engineers. In this paper, we explore to establish a unified failure criterion for defects with various geometries. First, a fundamental and universal law on failure that all criteria should follow, so-called the zeroth law of failure, is introduced, and the failure is completely governed by the local status of failure determining zone (FDZ), such as the stress distribution, material properties, and geometrical features. Failure criteria lacking a local dimension parameter within FDZ may have limited applicability, such as the traditional strength and fracture criteria. We choose the blunt V-notch as an example to demonstrate how to establish a unified failure criterion for quasi-brittle materials, and a series of experiments are carried out to verify its applicability. The proposed unified failure criterion and some existing failure criteria are also discussed and compared. The failure criteria that only include a single critical constant are incapable of reflecting the whole stress field information and local geometrical features of the FDZ. Our proposed unified failure criterion is expressed with a two-parameter function and has a wider applicability. [ABSTRACT FROM AUTHOR]

Oxygen transport from a systemic capillary to its surrounding tissue region in the hyperbaric environment is analyzed. Longitudinal and transversal diffusion in the capillary and tissue regions, convective effect of the blood, and equilibrium chemical kinetics of oxygen with hemoglobin are studied in this model. The effect of capillary wall permeability and capillary wall pressure gradient constant on the oxygen transport is also investigated in this study. The nonlinear oxyhemoglobin dissociation curve is considered at hyperbaric environment; further, the zeroth- and first-order oxygen uptake kinetics are considered for the oxygen consumption by the tissue cells. The analytical solution for the oxygen transport in both capillary and tissue regions is obtained using the method of eigenfunction expansion. It is noticed that the amount of oxygen consumption in the tissue region is larger with the first-order metabolism than the zeroth-order metabolism. It is also seen that in the first two-fifth part of the tissue, oxygen is delivered by longitudinal and transversal diffusion, and in the rest of the tissue, it is transported by transversal diffusion only. [ABSTRACT FROM AUTHOR]

The system considered in the present study consists of a heating furnace and a multipass recuperative heat exchanger for air preheating. Process design ensured the coordinated operation of this system by applying a basis of a probabilistic and informational approach to the organization of industrial systems. It proves optimal to increase the thermal load on the recuperative heat exchanger and decrease the thermal load on the furnace, without changing the overall heating parameters. Exergy analysis was used to validate the proposed solution and it was shown that the total exergy loss in a system with a heating furnace and a recuperative heat exchanger decreases in for recommended operating conditions. This results in fuel economy. [ABSTRACT FROM AUTHOR]