Related papers: Correlations in optical phonon spectra of complex …
It is shown that the nearest neighbor coupling between the carbon atoms is not enough to reproduce the phonon spectrum as observed in graphene, the second neighbor force constant is essential. For completeness we have rederived the phonon…
We investigate the influence of vibrational screening on the excitonic and optical properties of solids based on first-principles electronic-structure calculations. We solve the Bethe-Salpeter equation - the state-of-the-art description of…
Starting from the quantum Liouville equation for the density operator and applying the Weyl quantization, Wigner equations for the longitudinal and transversal optical and acoustic phonons are deduced. The equations are valid for any solid,…
We report the first measurement of the excitation spectrum and the static structure factor of a Bose-Einstein condensate. The excitation spectrum displays a linear phonon regime, as well as a parabolic single-particle regime. The linear…
We report on strong coupling of the charge carrier plasmon $\omega_{PL}$ in graphene with the surface optical phonon $\omega_{SO}$ of the underlying SiC(0001) substrate with low electron concentration ($n=1.2\times 10^{15}$ $cm^{-3}$) in…
We use the approximation-free Bold Diagrammatic Monte Carlo technique to study the effects of a finite dispersion of the optical phonon mode on the properties of the Holstein polaron, especially its effective mass. For weak electron-phonon…
Modification of optical phonon spectra in contacting nanoparticles as compared to the single ones is studied. Optical phonons in dielectric and semiconducting particles obey the Euclidean metric Klein-Fock-Gordon equation with Dirichlet…
A general coupled representation is proposed for bosonic atoms in double well optical lattices. Based on such a representation, we investigate the excitation spectra and thermodynamics of bosonic atoms in the optical lattices. We find…
The Born effective charges of component atoms and phonon spectra of a tetrahedrally coordinated crystalline ice are calculated from the first principles method based on density functional theory within the generalized gradient approximation…
Several recent studies show that bright, intermediate and high redshift optically and radio selected QSOs are positively correlated with nearby galaxies on a range of angular scales up to a degree. Obscuration by unevenly distributed…
The energy spectrum of the quantum Klein-Gordon lattice is computed numerically for different nonlinear contributions to the Hamiltonian. In agreement with the studies on the effective Hubbard Hamiltonian for boson quasi-particles (see for…
We present a random matrix approach to study general vibrational properties of stable amorphous solids with translational invariance using the correlated Wishart ensemble. Within this approach, both analytical and numerical methods can be…
We study a classical system of identically charged counter-ions near a planar wall carrying a uniform surface charge density. The equilibrium statistical mechanics of the system depends on a single dimensionless coupling parameter. A new…
We present a theory that efficiently describes the quantum dynamics of an electronic excitation that is coupled to a continuous, highly structured phonon environment. Based on a stochastic approach to non-Markovian open quantum systems, we…
A hallmark of structural glasses and other disordered solids is the emergence of excess low-frequency vibrations, on top of the Debye spectrum $D_{\rm Debye}(\omega)$ of phonons ($\omega$ denotes the vibrational frequency), which exist in…
High-harmonic spectroscopy of solids is a powerful tool, which provides access to both electronic structure and ultrafast electronic response of solids, from their band structure and density of states, to phase transitions, including the…
Unlike in ordinary metals, in graphene, phonon structure can be seen in the quasiparticle electronic density of states, because the latter varies on the scale of the phonon energy. In a magnetic field, quantization into Landau levels…
The tight-binding model is closely associated with the modified layer-based random-phase approximation to thoroughly investigate the electron-electron interactions in sliding bilayer graphene. The Coulomb interactions and intralayer and…
We calculate the interaction induced inhomogeneous broadening of spectral lines in a trapped Bose gas as a function of the depth of a three-dimensional cubic optical lattice. As observed in recent experiments, we find that the terraced…
We investigate the dynamics of a Bose-Einstein condensate in the presence of a random potential created by optical speckles. We first consider the effect of a weak disorder on the dipole and quadrupole collective oscillations, finding…