An admittance for localized physical quantities is generally related to a random walk on the basis of linear-response theory. A coherent-medium approximation introduced solve master equation which assumed govern walk. The general formalism specialized ac hopping conduction and applied bond-percolation model in one- three-dimensional systems lattice impurity doped semiconductors. For one-dimensional model, conductivity obtained by good agreement with exact results both frequency dependence...

We study the properties of one-dimensional quasilattices numerically and analytically. The geometrical general are discussed. Ising model on these lattices is studied by a decimation transformation: critical temperature exponents do not differ from those for regular periodic chain. vibrational spectrum in harmonic approximation analyzed numerically. system exhibits characteristics both disordered system. In low-frequency region, behaves as system; wave functions appear extended....

The tight-binding electronic structure of two-dimensional quasicrystals is studied numerically for three patterns Penrose tiling with up to 426 vertices. According the range interactions, different models are considered. For simplest model, two interactions assigned long and short edges tile. Energy spectra show several significant gaps whose width position depend on relative strength interactions. cumulative density states linear in energy at band edge, indicating existence Van Hove...

Dynamics of atoms near the glass transition simple classical liquids is studied on basis mesoscopic stochastic-trapping diffusion model recently developed by Odagaki [J. Phys. A 20, 6455 (1987); Rev. B. 38, 9044 (1988)]. The jump rate an atom (tracer) assumed to have a distribution following power-law function with exponent \ensuremath{\rho}, where \ensuremath{\rho} phenomenological parameter. sharp predicted at \ensuremath{\rho}=0, that is, self-diffusion vanishes when \ensuremath{\rho}<0...

The SIQR model is exploited to analyze the outbreak of COVID-19 in Japan where number daily confirmed new cases explicitly treated as an observable. It assumed that society consists four compartments; susceptible individuals (S), infected at large (I), quarantined patients (Q) and recovered (R), time evolution pandemic described by a set ordinary differential equations. shown quarantine rate can be determined from dependence cases, which estimated. infection are for period mid-February...

The exact frequency dependence of the ac hopping conductivity a one-dimensional chain with random interruptions is obtained. real and imaginary parts are shown to vanish quadratically linearly, respectively, at static limit. Critical behavior in limit no discussed.

We devise a method based on an analysis of the non-Gaussian parameter in finite time domain to determine transition between Gaussian and dynamics stochastic trapping model glass transition. find evidence Gaussian--to--non-Gaussian supercooled region soft-sphere fluids. propose alternative incoherent scattering function for glass-forming systems observe

Quantum percolation problems are studied with the use of a real-space renormalization-group method. A quantum effect is taken into account by calculating quantum-mechanical efficiency Kadanoff cell in opening channel for an electron cell. The threshold and critical index correlation length obtained both site bond square simplecubic lattices.

The ac conductivity of carriers which perform a random walk in environment is studied. Irreducible clusters hopping sites are introduced by connecting share nonzero jump rate. A finite irreducible random-walk matrix shown to be negative semidefinite and have nondegenerate zero eigenvalue. As result, the real imaginary parts systems without infinite vanish, respectively, quadratically linearly with frequency. coefficient linear dependence part related correlation length clusters. for...

Hopping conduction of a bond-percolation model in $d$-dimensional lattices is studied by making use the coherent-medium approximation. The dc conductivity vanishes when $p&lt;{p}_{c} (\ensuremath{\equiv}\frac{2}{z})$ and proportional to $p\ensuremath{-}{p}_{c}$ $p\ensuremath{\ge}{p}_{c}$, where $p$ probability that given bond not broken $z$ coordination number lattice. In low frequency region, leading term imaginary real parts ac part are written as $A(z,d,p)f(\ensuremath{\omega})$...

A percolation process concerned with the properties of quantum mechanical particles moving in a random medium is investigated numerically. The characteristics are introduced same manner as classical method: site problem, any has fixed probability x being unblocked, whereas bond p unblocked. If xcQ (or pcQ) maximum value p) for which particle attached to does not diffuse away, it shown both problems on square lattice that xcQ(pQc) very close critical case. one-particle density states such...

The dynamics of quasicrystals is more complicated than the periodic solids and difficult to study in experiments. Here, we investigate a decagonal dodecagonal quasicrystal using molecular simulations Lennard-Jones-Gauss interaction system. We observe that short time dominated by stochastic particle motion, so-called phason flips, which can be either single-particle jumps or correlated ring-like multi-particle moves. Over long times, flip mechanism efficient reordering generate diffusion....

Abstract The SIR or susceptible-infected-recovered model is the standard compartment for understanding epidemics and has been used all over world COVID-19. While assumes that infected patients are identical to symptomatic infectious patients, it now known in COVID-19 pre-symptomatic there significant number of asymptomatic who infectious. In this paper, population separated into five compartments COVID-19; susceptible individuals (S), (P), (A), quarantined (Q) recovered and/or dead (R). time...

The percolation theory is extended to a thermal equilibrium state of an interacting particle system. By computer simulation method, process in square lattice gas model studied super-critical regions. Critical density found be increasing function temperature. critical index probability almost independent temperature and 0.145±0.027. result obtained the applied metal-insulator transition fluid metals effect atomic configuration studied. A phase diagram obtained. aspect conductivity near point...

Atomic mechanism of glass formation a supercooled simple monatomic liquid with Lennard-Jones-Gauss (LJG) interatomic potential is studied by molecular dynamics (MD) simulation. Supercooled and glassy states are obtained cooling from the melt. Glassy state at low temperatures annealed for very long time, on order microsecond, we find that remains unchanged long-lived system in three dimensions realized. We analyze spatiotemporal properties solid-like liquid-like atoms defined Lindemann-like...

A simple monatomic system in two dimensions with a double-well interaction potential is investigated wide range of temperatures by molecular-dynamics simulation. The melted and equilibrated well above the melting temperature, then it quenched to temperature 88% below at several cooling rates produce an amorphous state. Various thermodynamic quantities are measured as functions while heated constant rate. glass transition observed sudden increase energy shown be increasing function rate...

Generalized susceptibility $\ensuremath{\chi}(\mathbf{q},\ensuremath{\omega})$ for binary soft-sphere mixtures is computed the first time a frequency range which includes both $\ensuremath{\alpha}$ and $\ensuremath{\beta}$ peaks in supercooled fluid phase with superlongtime (10 \ifmmode\times\else\texttimes\fi{} ${10}^{6}$ steps) molecular dynamics simulation. This gives us reliable spectral data wide of over 5 orders magnitude at various wave numbers, so that we can discuss without...

The homomorphic-cluster coherent-potential approximation is applied to obtain the average Green's function for spatially disordered systems in two and three dimensions, which described by a tight-binding one-electron Hamiltonian with transfer energy between $1s$ hydrogenic orbitals. effective medium be determined self-consistently assumed an appropriate lattice, modified Hertz distribution used random of nearest-neighbor distance. With use $L(E)$ criterion localization, Anderson's transition...