Showing papers in "Journal of the Physical Society of Japan in 1978"
TL;DR: In this article, the SCC-DV-Xα molecular orbital method was applied to metal clusters and the numerical basis functions were utilized in the present calculations, and it was proved that the self-consistent charge (SCC) approximation to the SCF method gives accurate orbital energies.
Abstract: Applications of the discrete variational (DV) Xα molecular orbital method based on the self-consistent Hartree-Fock-Slater model to metal clusters are presented. Numerical basis functions are utilized in the present calculations. Variations of orbital energies and populations with exchange scaling parameter α are investigated. It is proved that the self-consistent-charge (SCC) approximation to the SCF method gives accurate orbital energies. The numerical basis SCC-DV-Xα method is shown to be very efficient for studies of rather large metal clusters such as Ni 13 .
877 citations
TL;DR: In this article, the influence of electron concentration on the sequences of crystallographic transitions, on the magnetic ordering temperatures and on the constant (Pauli-type like) part of the magnetic susceptibility is discussed.
Abstract: In this study of metallic perovskites Mn 3 MX (M=metal, X=C, N) we emphasize the influence of the (outer) electron concentration on the sequences of crystallographic transitions, on the magnetic ordering temperatures and on the constant (Pauli-type like) part of the magnetic susceptibility. A great variety of observed magnetic structures and transitions (including spin rotations) are described for carbides and nitrides. The Labbe-Jardin tight binding model which invokes a p-d II hybridization between N and Mn orbitals having their energy levels near to the Fermi surface provides the possibility of great variations of the density of states versus temperature and is in qualitative agreement with experiment. It also explains that small substitutions on X have a more drastical effect than those can M.
317 citations
TL;DR: In this article, the authors dealt with weakly nonlinear long gravity waves on a stably stratified two-layer fluid and found that the fast mode is always governed by a Korteweg-de Vries (K-dV) equation whose coefficients depend on the thickness ratio and the density ratio.
Abstract: This paper deals with weakly nonlinear long gravity waves on a stably stratified two-layer fluid. By using the reductive perturbation method, it is found that the fast mode is always governed by a Korteweg-de Vries (K-dV) equation whose coefficients depend on the thickness ratio and the density ratio. On the other hand, the slow mode is also governed, in general, by another K-dV equation except near and at the critical thickness ratio. At the critical thickness ratio, however, the slow mode is shown to be governed by a modified K-dV equation with cubic nonlinearity and near the critical thickness ratio it is governed by an equation of a combined form of the K-dV and modified K-dV equation. Steady solitary wave solutions to these equations are investigated in detail. A special solution representing a dispersive bore or hydraulic jump is also found.
241 citations
TL;DR: In this paper, the authors extended the DV-Xα cluster method to ionic crystals with inclusion of the long-ranged Coulomb potential of the ions outside the cluster, and the surface and the bulk electronic structures of MgO crystal were calculated.
Abstract: Discrete variational (DV) Xα cluster method is extended to ionic crystals with inclusion of the long-ranged Coulomb potential of the ions outside the cluster. As a typical example of partially ionic crystals, the surface and the bulk electronic structures of MgO crystal are calculated. The strong electric field, the reduction in the Madelung potential and the charge redistribution on the surface are found to be important factors for the formation of the surface state. Various features of the DV-Xα cluster method, such as the size and the shape dependence of the cluster, the effect of the exterior potential and so on are investigated.
226 citations
TL;DR: In this article, a systematic perturbation method is applied to three-dimensional long waves on a viscous liquid film, and the nonlinear evolution equation incorporating the effects of dissipation and dispersion is derived.
Abstract: A systematic perturbation method is applied to three-dimensional long waves on a viscous liquid film, and the nonlinear evolution equation incorporating the effects of dissipation and dispersion is derived. It is shown that both the fourth-order derivative term as well as the three-dimensionality have stabilizing effects.
203 citations
TL;DR: In this article, the Curie temperature and magnetic susceptibility of itinerant electron ferromagnets are discussed from a general point of view by using a simple model with a small number of physical parameters and approximations in the functional integral formalism.
Abstract: Spin fluctuations and the thermodynamical properties of itinerant electron ferromagnets are discussed from a general point of view by using a simple model with a small number of physical parameters and approximations in the functional integral formalism. We give unified expressions for the Curie temperature and the magnetic susceptibility which interpolate between the weakly and strongly ferromagnetic limits. In general, both the transversal and longitudinal components of the local spin fluctuations contribute to the Curie constant and the former (latter) is predominant in the local moment (weakly ferromagnetic) limit. It is pointed out that the amplitude of the local spin fluctuations can be saturated when there is an upper or lower bound of the energy band not too far from the Fermi level, resulting in a Curie-Weiss susceptibility of a local moment type, even without well-defined local moments. A transition between two different kinds of local spin states can also be expected in some cases.
186 citations
TL;DR: In this article, the steady behavior of a gas in contact with its condensed phase of arbitrary shape is investigated on the basis of kinetic theory, and two simple examples (evaporation from a sphere, two-surface problem of evaporation and condensation) are worked out.
Abstract: The steady behavior of a gas in contact with its condensed phase of arbitrary shape is investigated on the basis of kinetic theory. The Knudsen number of the system (the mean free path of the gas molecules divided by the characteristic length of the system) being assumed to be fairly small, the hydrodynamic equations for the macroscopic quantities, the velocity, temperature, and pressure, of the gas and their boundary conditions on the interface of the gas and its condensed phase are derived, and two simple examples (evaporation from a sphere, two-surface problem of evaporation and condensation) are worked out.
164 citations
TL;DR: In this article, a quasi-one-dimensional antiferromagnet of Ising-like spins of CsCoCl 3 was measured in the long range ordered region at 4.2 K and the critical exponent of the magnetization was found to be 0.34 around the Neel temperature 20.82 K.
Abstract: Neutron diffraction measurements were carried out on single crystals of CsCoCl 3 , a quasi-one-dimensional antiferromagnet of Ising-like spins, in the long range ordered region. The determined magnetic structure at 4.2 K is composed of antiferromagnetic stacking of ferrimagnetic c -plane with three sublattices as determined by Melamud et al. The spins are aligned along c -axis and were evaluated to be 3.11 µ B at 0 K by extrapolation. Unusual temperature dependence of magnetic reflection intensity was observed and interpreted as a partial disordering transition in which one of the three sublattices in a c -plane loses its magnetization above 13.5 K resulting in antiferromagnetic c -planes. This transition is discussed in connection with the antiferro-ferrimagnetic transition in the triangular Ising lattice. The critical exponent of the magnetization was found to be 0.34 around the Neel temperature 20.82 K.
163 citations
TL;DR: In this article, the authors show that tetramethylammonium tetrachlorozincate exhibits ferroelectricity along a axis in the temperature range between 3.3 and 6.0°C.
Abstract: Tetramethylammonium tetrachlorozincate, {N(CH 3 ) 4 } 2 ZnCl 4 has been found to undergo successive phase transitions at about -112, -92, 3.3, 6.0 and 20°C and to show ferroelectricity along the a axis in the temperature range between 3.3 and 6.0°C.
141 citations
TL;DR: In this article, the higher order approximations in reductive perturbation method are studied for the weakly dispersive nonlinear system, and it is shown that the secular terms appearing in the high order terms are eliminated by adding to the Korteweg-de Vries equation the derivatives of the higher-order conserved densities, the physical effects of which are given by the renormalization of the velocities of the KdV solitons.
Abstract: The higher order approximations in the reductive perturbation method are studied for the weakly dispersive nonlinear system. It is shown that the secular terms appearing in the high order terms are eliminated by adding to the Korteweg-de Vries equation the derivatives of the higher-order conserved densities, the physical effects of which are given by the renormalization of the velocities of the KdV solitons.
136 citations
TL;DR: In this article, the inverse method related to a modified Zakharov-Shabat eigen value problem with nonvanishing potentials q ( x ) and r ( x ), where q(x) and r(x ) is developed.
Abstract: The inverse method related to a modified Zakharov-Shabat eigen value problem with nonvanishing potentials q ( x ) and r ( x ), where \(q({\pm}\infty)r({\pm}\infty){=}\lambda^{2}_{0}{\lessgtr}0\) is developed. There exists a certain class of the nonlinear evolution equations which are solvable by this method. As the most primitive case a derivative nonlinear Schrodinger equation, i q t + q x x - m i(| q | 2 q ) x =0( m =-1, +1), is solved under the nonvanishing boundary condition, | q | 2 → m λ 2 0 as x →±∞. There appear paired-solitons because of the nonvanishing condition. One paired-soliton solution is obtained with the closed form. This solution shows an algebraic behaviour under a certain limiting condition.
TL;DR: The theory of a one-dimensional lattice gas with long-range many-body interactions is applied to the folding pathways of proteins and the quantitative informations about the order of inter-residue interactions, the location of nucleation and so on are presented.
Abstract: The theory of a one-dimensional lattice gas with long-range many-body interactions is applied to the folding pathways of proteins. This model presents the quantitative informations about the order of inter-residue interactions, the location of nucleation and so on. Three typical proteins are cited as examples and their folding pathways are traced according to the computation of some useful properties.
TL;DR: In this paper, the thickness of the lipid bilayer and the water layer were determined with X-rays for dipalmitoyl phosphatidylcholine lamellar phase.
Abstract: Thicknesses d l of the lipid bilayer and d w of the water layer were determined separately with X-rays for dipalmitoyl phosphatidylcholine lamellar phase. In both cases of the presence and the absence of excess water, d l does not change appreciably at the pretransition (35°C) but drops down by about 5 A at the main transition (42°C) with increasing temperature. In the presence of excess water, d w jumps up by 4.0 A at the pretransition and by 2.0 A at the main transition. These results prove that there is practically no change of the tilting angle of hydrocarbon chains at the pretransition and that the remarkable increase of the repeat distance of the lamellar phase at the pretransition in the presence of excess water is caused by the increase of the thickness of the water layer.
TL;DR: In this article, an extended inverse scattering method is developed to solve the nonlinear evolution equations which are based on the AKNS eigenvalue problem with nonvanishing potentials q(x)r(x){\rightarrow}\lambda_{0}^{2}({\gtrless}0)\) as x →±∞.
Abstract: An extended inverse scattering method is developed to solve the nonlinear evolution equations which are based on the AKNS eigenvalue problem with nonvanishing potentials q ( x ) and r ( x ) where \(q(x)r(x){\rightarrow}\lambda_{0}^{2}({\gtrless}0)\) as x →±∞. As an example, we solved the case of nonlinear Schrodinger equation, i q t + q x x -2( m | q | 2 -λ 0 2 ) q =0 ( m =-1, +1), under the nonvanishing boundary conditions, q ( x , t )→ q ± as x →±∞, where q ± are constants. For m =1 we get the “envelope dark soliton,” while for m =-1 there appears a new solution as the extended form of the “envelope bright soliton.”
TL;DR: In this article, the successive phase transitions from a prototype to an incommensurate phase and then to a commenurate phase are studied on the basis of a model thermodynamic potential where the instability of a one-dimensional representation is assumed.
Abstract: The successive phase transitions from a prototype to an incommensurate phase and then to a commensurate phase are studied on the basis of a model thermodynamic potential where the instability of a one-dimensional representation is assumed. The model is suitable to a unified description of the phase transitions in SC(NH 2 ) 2 and NaNO 2 which show ferroelectricity in their commensurate phases. The incommensurate states of the model and its dielectric properties are analysed by taking harmonics into account. It has turned out that the present model can satisfactorily reproduce the transitions actually observed in SC(NH 2 ) 2 and NaNO 2 .
TL;DR: In this paper, a one-dimensional lattice gas with long-range many-body interactions is studied by a matrix method for the model of the transition between native and denatured states of globular proteins.
Abstract: A one-dimensional lattice gas with long-range many-body interactions is studied by a matrix method for the model of the transition between native and denatured states of globular proteins. The interactions in our model have the nature that two particles situated on two different sites can interact with each other only when all sites between them are occupied by other particles, or in other words, only when they are in a same island which is formed by particles situated side by side. In this system a phase transition occurs in the limit of the infinite long-range interaction and under certain potential functions. The sharpness and the all-or-none type property of the transitions are discussed from the nature of interaction.
TL;DR: The possibility of superconductivity with the aid of the plasmon in two-and three-dimensional single-carrier systems is investigated by numerical solutions of the gap equation in the weak-coupling theory of super-conductivity as discussed by the authors.
Abstract: The possibility of the superconductive state with the aid of the plasmon in two- and three-dimensional single-carrier systems is investigated by numerical solutions of the gap equation in the weak-coupling theory of superconductivity, in which the effective interactions are calculated in the plasmon-pole approximation. The superconductivity does appear in rather low carrier concentrations and the highest attainable transition temperature is of the order of m * /κ 2 degrees Kelvin, where the effective mass, m * , is in the unit of the mass of a free electron and κ is the dielectric constant. Compared with a three-dimensional system, a two-dimensional one is more favorable for the plasmon mechanism of superconductivity, which stems from the difference in the dispersion relation of the plasmon.
TL;DR: The complex dielectric constants parallel and normal to the optical axis in a single crystal were measured in a wide range of the temperature (0°∼-150°C).
Abstract: The complex dielectric constants parallel and normal to the optical axis in ice Ih single crystal were measured in a wide range of the temperature (0°∼-150°C). T h e s t a t i c d i e l e c t r i c c o n s t a n t o f t h e D e b y e c o m p o n e n t a t e a c h t e m p e r a t u r e w a s o b t a i n e d b y e x t r a p o l a t i n g o n t h e C o l e - C o l e p l o t t o z e r o f r e q u e n c y . D i e l e c t r i c a n i s o t r o p y a g r e e d w e l l t h a t o f H u m b e l et al . a t h i g h t e m p e r a t u r e s , a n d i t i n c r e a s e d w i t h d e c r e a s i n g t e m p e r a t u r e . T h e s t a t i c d i e l e c t r i c c o n s t a n t e ^//_s f o l l o w e d a C u r i e - W e i s s l a w w h e r e T_0 w a s 46 K a n d i t s C u r i e - W e i s s c o n s t a n t C_// w a s 2.25×10^4 K , w h i l e e ^⊥_s o b e y e d a C u r i e l a w w h e r e C u r i e c o n s t a n t C_⊥ w a s 2.37×10^4 K . T h e s e r e s u l t s s t r o n g l y s u g g e s t t h e a n i s o t r o p y i n d i p...
TL;DR: The flow around a circular cylinder performing a rotatory oscillation about its axis in a uniform flow has been investigated experimentally by means of flow visualization methods at Reynolds numbers between 30 and 300 and Strouhal numbers between 0 and 55 as discussed by the authors.
Abstract: The flow around a circular cylinder performing a rotatory oscillation about its axis in a uniform flow has been investigated experimentally by means of flow visualization methods at Reynolds numbers between 30 and 300 and Strouhal numbers between 0 and 55. It has been found that the dead water region is reduced as the frequency of the oscillation is increased, and that the critical Strouhal number at which the dead water region vanishes is approximately proportional to the reciprocal of the angular amplitude of oscillation, but is independent of the Reynolds number. It has also been found that when the Strouhal number is much higher than the critical Strouhal number the flow past the cylinder is strongly accelerated.
TL;DR: In this article, the peak energy, line width and polarization of these lines depend strongly on the direction of observation and the geometrical configuration of two excitation laser beams, from which the nonlinear effect on the polariton dispersion associated with the giant two-photon absorption is found.
Abstract: Two polariton scattering in resonance with giant two-photon excitation of excitonic molecule in CuCl has been measured in various scattering configurations with using single-beam and two-beam excitation methods. Several scattering lines are found, the peak energies of which depend strongly not only on the direction of observation but also on the geometrical configuration of two excitation laser beams. Dependence of the peak energy, line width and polarization of these scattering lines upon the incident energy and the excitation power has been investigated in details, from which the non-linear effect on the polariton dispersion associated with the giant two-photon absorption is found.
TL;DR: A Backlund transformation in the bilinear form for the Toda equation is presented in this article, which generates a class of nonlinear partial difference equations that exhibits solitons.
Abstract: A Backlund transformation in the bilinear form is presented for the discrete-time Toda equation. The Backlund transformation generates a class of nonlinear partial difference equations that exhibits solitons.
TL;DR: In this article, a nonlinear transmission line equivalent to the exponential lattice of Toda was obtained with the proper understanding of nonlinear properties of a capacitor used in a shunt branch, and the character of a soliton was observed to follow the prediction given by Toda with respect to the shape and velocity of the soliton.
Abstract: A nonlinear transmission line equivalent to the exponential lattice of Toda was obtained with the proper understanding of nonlinear properties of a capacitor used in a shunt branch. The character of a soliton is observed to follow the prediction given by Toda with respect to the shape and velocity of the soliton. The details of interaction of two solitons moving in the opposite or same direction are also found to be in good agreement with the theory. The dissipation effect on the soliton due to the small losses in the passive elements of the network is discussed in the continuum limit.
TL;DR: In this paper, the nature of the ferromagnetic interactions in cubic-perovskite type ARu 4+ O 3 (A=nonmagnetic cation) was investigated by using a magnetic balance technique.
Abstract: To clarify the nature of the ferromagnetic interactions in SrRuO 3 , the Ru 4+ – –Ru 4+ exchange couplings in cubic-perovskite type ARu 4+ O 3 (A=nonmagnetic cation) were investigated Magnetic measurements were done on these sample oxides (including single crystals of CaRuO 3 ) by using a magnetic balance technique In contrast to the ferromagnetic behaviors in (Ca 1- x Sr x )RuO 3 ( x ≧04), both the (La 05 Na 05 )RuO 3 metallic and (Ca 1- x Mg x )RuO 3 ( x =01, 03 and 05) semiconductive systems were found to be Curie-Weiss paramagnets having negative asymptotic Curie points On the (Ca 08 Sr 08 )RuO 3 sample, an anomalous hump of χ vs T curve was observed, which could be interpreted as being due to ferromagnetic clusters of Sr 2+ It was suggested that, besides the 180° superexchange coupling, another indirect-exchange interaction via Sr 2+ would be indispensable for the ferromagnetism in SrRuO 3
TL;DR: In this paper, a new model is proposed for the excitonic mechanism of defect formation in alkali halides by ionizing radiation, and the bottleneck governing the time of formation is the non-radiative transition from the second lowest state (2 p z ) to the lowest state of the electron bound by the self-trapped hole.
Abstract: A new model is proposed for the excitonic mechanism of defect formation in alkali halides by ionizing radiation. The bottleneck governing the time of formation is the non-radiative transition from the second lowest state (2 p z ) to the lowest state (1 s ) of the electron bound by the self-trapped hole. The adiabatic instability of the lower state originating from the mixing and anticrossing of the two states of the electron in the double well potential generates a force squeezing out the central anion pair into [110] direction, which restults in the replacement sequence ending as H center on the one hand, and in F center left behind in its ground state (because of node number conservation) on the other hand. The model is consistent with a variety of experimental facts so far reported.
TL;DR: In this paper, the phase transition of KD 3 (SeO 3 ) 2 accompanied an instability of the soft s 44 mode alone, as in the case of KK 3, SeO 3, 2.
Abstract: Ultrasonic velocities at 5 and 10 MHz and spontaneous strains of KD 3 (SeO 3 ) 2 were measured and the results were compared with those for KH 3 (SeO 3 ) 2 . Elastic constants were obtained from the velocity data. The phase transition of KD 3 (SeO 3 ) 2 accompanies an instability of the soft s 44 mode alone, as in the case of KH 3 (SeO 3 ) 2 . Deuteration yields no significant isotope effect in the Curie-Weiss constant C s , although it gives large isotope effect in the transition temperature T c .
TL;DR: In this paper, the numerical solutions of phase transitions under the existence of the Lifshitz invariant are presented, and the temperature dependences of thermodynamic potential and dielectric susceptibility are shown for some values of coefficients appearing in a model thermodynamics potential.
Abstract: The numerical solutions of the phase transitions under the existence of the Lifshitz invariant are presented. The temperature dependences of thermodynamic potential and dielectric susceptibility are shown for some values of coefficients appearing in a model thermodynamic potential. The feature of space modulation of order parameters is also shown. The results will be discussed in the relationship with some ferroelectric materials in which the incommensurate phase is actually realized in some temperature range.
TL;DR: In this paper, the Backlund transformation is used to construct the superposition formulae for soliton solutions from nonlinear evolution equations, such as the Korteweg-de Vries (KdV), Boussinesq, modified KdV, Sine-Gordon and Toda equations.
Abstract: Superposition formulae for soliton solutions are constructed from the Backlund transformation. The nonlinear evolution equations concerned are the Korteweg-de Vries (KdV), Boussinesq, two-dimensional KdV, modified KdV, Sine-Gordon and Toda equations. It is shown that the superposition formulae have a common simple structure when they are written in the bilinear forms.
TL;DR: In this paper, the Perturbed Rotational State approach is used to calculate the rotational excitation cross sections of a collision between a proton and a CN molecule and a scaling law is derived.
Abstract: Ion-Polar molecule collisions are studied in the Perturbed Rotational State approach. The basic idea is that the molecular rotation is nearly adiabatically deformed during the collision. The semiclassical, impact-parameter method is adopted. This formulation of the collision problem gives an easy way to calculate the rotational excitation cross sections. Numerical examples are given for the low-energy collision between a proton and a CN molecule. A scaling law is derived so that the numerical results obtained can be used also for many other collision systems.
TL;DR: It has been found that K 2 ZnCl 4 shows ferroelectric activity below the Curie point of 123°C (on cooling process) and spontaneous polarization is about 0.15 µCcm -2 at room temperature as discussed by the authors.
Abstract: It has been found that K 2 ZnCl 4 shows ferroelectric activity below the Curie point of 123°C (on cooling process). The spontaneous polarization is about 0.15 µCcm -2 at room temperature.