Electron-pinned defect dipoles, in the form of highly stable triangle-diamond and/or triangle-linear dopant clusters with well defined relative positions for Ti reduction, are present rutile In + Ta co-doped TiO₂ colossal permittivity and low loss.

The polaron energy and effective mass are calculated for an electron in a quantum-well structure the absence of magnetic field. Interaction with interface optical-phonon modes confined slab LO-phonon incorporated calculation, comparison is made results which phonons assumed to be three dimensional (3D). Three different confining potentials investigated: (1) parabolic well, (2) infinite-barrier quantum (3) finite-barrier well. A detailed study has been importance incorporating levels. Our...

The transition energies between the ground state (1s-like) and two excited states (2${\mathit{p}}^{\ifmmode\pm\else\textpm\fi{}}$-like) are calculated for shallow donor impurities in GaAs superlattices presence of a magnetic field along growth axis. Results obtained as function well width various widths heights barriers superlattices. dependence on position donors effect band nonparabolicity also investigated. calculation is based variational approach which Gaussian-type trial wave functions...

We investigate the energetic and structural properties of small lithium clusters doped with a carbon atom using combination computational methods, including density functional theory (DFT), diffusion quantum Monte Carlo (DMC), Hartree–Fock (HF) approximation. calculate lowest energy structures, total ground-state energies, electron populations, binding dissociation energies as function cluster size. Our results show that doping significantly enhances stability clusters, increasing magnitude...

The electron optical-phonon coupling is studied in GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As quantum wells as due to the interface modes, confined slab modes well, and half-space barriers. polaron binding energy effective mass are calculated relative importance of different phonon investigated a function width well. full spectrum, i.e., discrete levels well continuum spectrum above barrier, included intermediate states. go continuously from...

Using fixed node diffusion quantum Monte Carlo (FN-DMC) simulations and density functional theory (DFT) within the generalized gradient approximations, we calculate total energies of relaxed unrelaxed neutral, cationic, anionic aluminum clusters, Al${}_{n}$ ($n=1--13$). From obtained energies, extract ionization potential electron detachment energy compare with previous theoretical experimental results. Our results for electronic properties from both FN-DMC DFT calculations are in reasonably...

We investigate dc and ac transport in silicene the presence of a perpendicular electric field Ez that tunes its band gap, finite temperatures, level broadening. The interplay silicene's strong spin-orbit interaction gives rise to topological phase transitions. show at critical value spin-Hall conductivity undergoes transition from insulator one. also spin- valley-Hall conductivities exhibit temperature dependence. In addition, longitudinal is examined as function carrier density ne, for...

The electron transport properties in \ensuremath{\delta}-doped semiconductor systems are studied. subband electronic structure of the system is obtained by solving coupled Schr\"odinger and Poisson equations. screening quasi-two-dimensional gas taken into account for ionized impurity scattering through matrix dielectric function within random-phase approximation. quantum mobilities calculated numerically as a total density width doped layer at zero temperature. intersubband effect empty...

The effects of interface optical-phonon and confined slab LO-phonon modes on the polaron cyclotron-resonance frequency are investigated for a GaAs/AlAs quantum well. Using degenerate second-order perturbation theory, Landau levels calculated resonant region is investigated. In order to know relative importance different frequencies we present full calculation magneto-optical absorption spectrum. At fixed magnetic field found four peaks in oscillator strength changes with increasing field....

We study the structural phase transitions in confined systems of strongly interacting particles. consider infinite quasi-one-dimensional with different pairwise repulsive interactions presence an external confinement following a power law. Within framework Landau's theory, we find necessary conditions to observe continuous and demonstrate that only allowed transition is between single- double-chain configurations it takes place when parabolic. determine analytically behavior system at point...

The mobility of electrons in a quasi-one-dimensional channel on the surface liquid helium is studied theoretically at temperatures lower than 1.5 K. influence due to electron-ripplon interaction and electron scattering from atoms vapor phase investigated. nonmonotonic temperature dependence below 0.5 K attributed contribution coming matrix elements operators between different subbands confinement motion along channel. It shown that results taking electron-electron correlations into account...

In order to study quantum effects in a two-dimensional crystal lattice of free-standing monolayer graphene, we have performed both path-integral Monte Carlo (PIMC) and classical (MC) simulations for temperatures up 2000 K. The REBO potential is used the interatomic interaction. total energy, distance, root-mean-square displacement atom vibrations, free energy graphene layer are calculated. obtained vibrational per from MC simulation very close three-dimensional harmonic oscillator...

We extend the unsymmetrized self-consistent-field method (USF) for anharmonic crystals to layered non-Bravais investigate structural, dynamical and thermodynamic properties of a free-standing graphene monolayer. In this theory, main anharmonicity crystal lattice has been included quantum corrections are taken into account in an ℏ-expansion one-particle density matrix. The obtained result thermal expansion coefficient (TEC) shows strong temperature dependence agrees with experimental results...

Using fixed-node diffusion quantum Monte Carlo (DMC) simulation we investigate the structural properties and energetics of linear cyclic carbon clusters ${\mathrm{C}}_{n}$ for $n\ensuremath{\le}10$. We calculate binding energy, electron correlation dissociation second difference in energy. also present an analysis clusters. It is found that bond lengths, energies, energies obtained from DMC calculations are excellent agreement with available experimental results. The electron-correlation...

The magnetopolaron is investigated in parabolic quantum wells the presence of a tilted magnetic field. Landau levels polarons $\mathrm{GaAs}/{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x}\mathrm{As}$ are calculated for different subbands. effect electron-phonon interaction on polaron energy included within second-order perturbation theory. influence direction field electron studied. Possible resonances also discussed.

The effects due to intersubband coupling and screening on the ionized impurity scattering are studied for a quasi-two-dimensional electron system in δ-doped semiconductors. We found that plays an essential role describing properties effect of mobility multisubband system. At onset occupation higher subband, leads reduction small angle rate lower subband. showed such is significant quantum well results pronounced increase at

The screening of the electron-phonon interaction due to a quasi-one-dimensional (Q1D) electron gas is investigated. contribution ground-state energy Q1D polaron in different semiconductor quantum-well-wire structures calculated within Hartree-Fock and random-phase approximation. influences width quantum-well wire density on are studied. We found that reduces effective coupling system appreciably decreases with increasing density.

Polaron cyclotron resonance (CR) has been studied in three modulation-doped $\mathrm{GaAs}/\mathrm{Al}{}_{0.3}{\mathrm{Ga}}_{0.7}\mathrm{As}$ multiple quantum well structures magnetic field up to 30 T. Large avoided-level-crossing splittings of the CR near GaAs reststrahlen region, and smaller region AlAs-like optical phonons th AlGaAs barriers, are observed. Based on a comparison with detailed theoretical calculation, high frequency splitting, magnitude which increases decreasing width, is...

The persistent current in two vertically coupled quantum rings containing few electrons is studied. We find that the Coulomb interaction between absence of tunneling affects each ring and ground-state configurations. Quantum alters significantly ground state system.

Using the fixed-node diffusion quantum Monte Carlo method, we calculate total energy of small cationic and neutral lithium clusters. We estimate ionization potential, atomic binding energy, dissociation second difference in energy. present a critical analysis structural electronic properties The bond lengths energies obtained from calculations are excellent agreement with available experimental results. A comparative indicates that clusters Li3+, Li5+, Li7+ most stable ones. have also...

Using fixed-node diffusion quantum Monte Carlo (FN-DMC) simulation we investigate the electron correlation in all-metal aromatic clusters MAl4(-) (with M = Li, Na, K, Rb, Cu, Ag and Au). The detachment energies affinities of are obtained. vertical obtained from FN-DMC calculations very good agreement with available experimental results. Calculations also performed within Hartree-Fock approximation, density-functional theory (DFT), couple-cluster (CCSD(T)) method. From results, analyse impact...

We theoretically study the plasmon modes in double parallel metallic armchair graphene nanoribbons (AGNRs) separated by a distance ${L}_{b}$. Starting with single doped AGNR at zero temperature, we show dispersion dependence on Fermi wave vector. By evaluating static dielectric function for this ribbon, find that usual logarithmic divergence $q=2{k}_{F}$ is absent. This indicates plasmons AGNRs might be most robust charge-density oscillations occurring quasi-one-dimensional electron systems....

We study the commensurability oscillations in silicene subject to a perpendicular electric field Ez, weak magnetic B, and periodic potential V=V0cos(Cy),C=2π/a0 with a0 its period. The Ez and/or modulation lift spin degeneracy of Landau levels lead valley resolved Weiss oscillations. resolution is maximal when replaced by one Ez=E0cos(Dy),D=2π/b0, while for b0 = a0. In certain ranges B values, current fully or polarized. Additional quantum Hall conductivity plateaux arise due...

We present a theoretical study on the electron mobility and scattering mechanism in remotely doped AlGaAs wide parabolic quantum well. Electron mobilities different subbands are calculated from self-consistent results of subband energy wavefunction system. The due to ionized impurities alloy disorder is considered. show theinterplay mechanisms.