A cross-platform program, VESTA, has been developed to visualize both structural and volumetric data in multiple windows with tabs. VESTA represents crystal structures by ball-and-stick, space-filling, polyhedral, wireframe, stick, dot-surface and thermal-ellipsoid models. A variety of crystal-chemical information is extractable from fractional coordinates, occupancies and oxidation states of sites. Volumetric data such as electron and nuclear densities, Patterson functions, and wavefunctions are displayed as isosurfaces, bird's-eye views and two-dimensional maps. Isosurfaces can be colored according to other physical quantities. Translucent isosurfaces and/or slices can be overlapped with a structural model. Collaboration with external programs enables the user to locate bonds and bond angles in the `graphics area', simulate powder diffraction patterns, and calculate site potentials and Madelung energies. Electron densities determined experimentally are convertible into their Laplacians and electronic energy densities.

VESTA: a three-dimensional visualization system for electronic and structural analysis

Statistical physics has proven to be a fruitful framework to describe phenomena outside the realm of traditional physics. Recent years have witnessed an attempt by physicists to study collective phenomena emerging from the interactions of individuals as elementary units in social structures. A wide list of topics are reviewed ranging from opinion and cultural and language dynamics to crowd behavior, hierarchy formation, human dynamics, and social spreading. The connections between these problems and other, more traditional, topics of statistical physics are highlighted. Comparison of model results with empirical data from social systems are also emphasized.

Statistical physics of social dynamics

Since the subject of traffic dynamics has captured the interest of physicists, many surprising effects have been revealed and explained. Some of the questions now understood are the following: Why are vehicles sometimes stopped by ``phantom traffic jams'' even though drivers all like to drive fast? What are the mechanisms behind stop-and-go traffic? Why are there several different kinds of congestion, and how are they related? Why do most traffic jams occur considerably before the road capacity is reached? Can a temporary reduction in the volume of traffic cause a lasting traffic jam? Under which conditions can speed limits speed up traffic? Why do pedestrians moving in opposite directions normally organize into lanes, while similar systems ``freeze by heating''? All of these questions have been answered by applying and extending methods from statistical physics and nonlinear dynamics to self-driven many-particle systems. This article considers the empirical data and then reviews the main approaches to modeling pedestrian and vehicle traffic. These include microscopic (particle-based), mesoscopic (gas-kinetic), and macroscopic (fluid-dynamic) models. Attention is also paid to the formulation of a micro-macro link, to aspects of universality, and to other unifying concepts, such as a general modeling framework for self-driven many-particle systems, including spin systems. While the primary focus is upon vehicle and pedestrian traffic, applications to biological or socio-economic systems such as bacterial colonies, flocks of birds, panics, and stock market dynamics are touched upon as well.

Traffic and related self-driven many-particle systems

A large body of work has been reported in the last 5 years on the development of lead-free piezoceramics in the quest to replace lead–zirconate–titanate (PZT) as the main material for electromechanical devices such as actuators, sensors, and transducers. In specific but narrow application ranges the new materials appear adequate, but are not yet suited to replace PZT on a broader basis. In this paper, general guidelines for the development of lead-free piezoelectric ceramics are presented. Suitable chemical elements are selected first on the basis of cost and toxicity as well as ionic polarizability. Different crystal structures with these elements are then considered based on simple concepts, and a variety of phase diagrams are described with attractive morphotropic phase boundaries, yielding good piezoelectric properties. Finally, lessons from density functional theory are reviewed and used to adjust our understanding based on the simpler concepts. Equipped with these guidelines ranging from atom to phase diagram, the current development stage in lead-free piezoceramics is then critically assessed.

Perspective on the Development of Lead-free Piezoceramics

Statistical physics of vehicular traffic and some related systems

We have used a lattice model based on the Landau-Ginzburg theory to examine the ferroelectric properties of a strongly coupled superlattice consisting of alternating ferroelectric and paraelectric layers. The thickness effects of the ferroelectric and paraelectric layers on the polarization behaviors of the superlattice are examined in relation to the dielectric softness of the paraelectric layer. Our finding suggests that the properties of the superlattice do not arise just from the intrinsic property of the ferroelectric layer alone, but depends on the behavior of the paraelectric layers. The competition between the thickness effects from the ferroelectric and paraelectric layers is found to play an important role in determining the properties of a superlattice. ** Present Address: School of Physics, University of Western Australia, 35 Stirling Highway, Crawly, WA 6009 Australia.

Competition Between the Thickness Effects of Each Constituent Layer in Ferroelectric Superlattices

Formation of KNO 3 Solid State Battery

The holding characteristic of the dark state of antiferroelectric liquid crystal (AFLC) displays have a crucial effect on the contrast ratio. We have studied the dependence of the transmittance in the dark state on the waveform of the applied voltage in multiplex driving for several materials. The samples used were 4-(1-methylheptyloxycarbonyl)phenyl-4'-octyloxybiphenyl-4-carboxylate (MHPOBC) and its homologues. It was found that the holding characteristics of the dark state are affected by the applied waveforms and the chemical structures such as the type of chiral radical and the length of the alkyl chain.

Holding Characteristic of Dark State in Antiferroelectric Liquid Crystal

On making use of the combinatorial method for evaluating entropy, a free energy function is derived to explain ferroelectric and antiferroelectric phase transitions in CsH 2 PO 4 crystal which has one-dimensional hydrogen-bond chains In addition to the pressure vs temperature phase diagram, the applied electric field vs temperature phase diagram in case of the antiferroelectric phase transition is discussed The dielectric hysteresis loops in the antiferroelectric phase are presented

On Phase Diagram of CsH2PO4 with Pseudo One-Dimensional Ferroelectric and Antiferroelectric Ordering

The ferroelastic behavior of relaxor 24Pb(In1/2Nb1/2)O3–46Pb(Mg1/3Nb2/3)O3–30PbTiO3 (PIN–PMN–PT) solid-solution single crystals was investigated under shear stresses using polarization light microscopy (PLM) and the scanning electron microscopy (SEM). Optical strain patterns along the \(\{110\}_{\text{cub}}\) directions from the orthoscope images under crossed Nicol, induced by shear stresses applied along the \([001]_{\text{cub}}\) direction, making use of a Vickers microindenter with a square-base diagonal line oriented along the \(\{100\}_{\text{cub}}\) directions of the crystal were observed on its \((001)_{\text{cub}}\) plate for the first time. These patterns at a diagonal position reveal a flowerlike pattern for ferroelastic transition from a square (S) lattice to a rectangular (R) lattice in a two-dimensional model system. A change in the interference color from yellow to blue through red toward the center in their flower leaves, according to the Michel–Levy birefringence chart, was observed. The ...

Yoshihiro Ishibashi

Papers

Competition Between the Thickness Effects of Each Constituent Layer in Ferroelectric Superlattices

Formation of KNO 3 Solid State Battery

Holding Characteristic of Dark State in Antiferroelectric Liquid Crystal

On Phase Diagram of CsH2PO4 with Pseudo One-Dimensional Ferroelectric and Antiferroelectric Ordering

Ferroelastic Behavior in Relaxor 24Pb(In1/2Nb1/2)O3–46Pb(Mg1/3Nb2/3)O3–30PbTiO3 under Shear Stresses along [001] Direction