M.O. Sales

Electron–soliton dynamics in chains with cubic nonlinearity

In our work, we consider the problem of electronic transport mediated by coupling with solitonic elastic waves. We study the electronic transport in a 1D unharmonic lattice with a cubic interaction between nearest neighboring sites. The electron-lattice interaction was considered as a linear function of the distance between neighboring atoms in our study. We numerically solve the dynamics equations for the electron and lattice and compute the dynamics of an initially localized electronic wave-packet. Our results suggest that the solitonic waves that exist within this nonlinear lattice can control the electron dynamics along the chain. Moreover, we demonstrate that the existence of a mobile electron-soliton pair exhibits a counter-intuitive dependence with the value of the electron-lattice coupling.

Sub-diffusive electronic transport in a DNA single-strand chain with electron–phonon coupling

We investigate the electronic wavepacket dynamics in a finite segment of a DNA single-strand chain considering the electron-phonon coupling. Our theoretical approach makes use of an effective tight-binding Hamiltonian to describe the electron dynamics, together with a classical harmonic Hamiltonian to treat the intrinsic DNA vibrations. An effective time-dependent Schrödinger equation is then settled up and solved numerically for an initially localized wave-packet using the standard Dormand-Prince eighth-order Runge-Kutta method. Our numerical results indicate the presence of a sub-diffusive electronic wavepacket spread mediated by the electron-phonon interaction.

Dynamics of interacting electrons under effect of a Morse potential

We consider interacting electrons moving in a nonlinear Morse lattice. We set the initial conditions as follows: electrons were initially localized at the center of the chain and a solitonic deformation was produced by an impulse excitation on the center of the chain. By solving quantum and classical equations for this system numerically, we found that a fraction of electronic wave function was trapped by the solitonic excitation, and trapping specificities depend on the degree of interaction among electrons. Also, there is evidence that the effective electron velocity depends on Coulomb interaction and electron-phonon coupling in a nontrivial way. This association is explained in detail along this work. In addition, we briefly discuss the dependence of our results with the type of initial condition we choose for the electrons and lattice.

Absorption Spectra And Level Spacing Statistics In A Ternary Alloy With An Ornstein–Uhlenbeck Disorder Distribution

In this paper, we study the dynamics of a one-electron in a one-dimensional (1d) alloy with a correlated Ornstein–Uhlenbeck (OU) disorder distribution. The model considered here corresponds to an alloy with three types of atoms where the position of each atom is obtained using a stochastic rule based on the OU process. We analyze in detail the effect of this correlated disorder in the optical absorption spectrum and the level spacing statistics near the band center. Our results reveal a new collection of optical absorption peaks. We explain in details the appearance of each peak. Our calculations about the level spacings distribution reveals a Poisson distribution thus contradicting previous statements about the existence of extended states in ternary electronic models with correlated disorder distribution.

One-electron propagation in Fermi, Pasta, Ulam disordered chains with Gaussian acoustic pulse pumping

In this work, we consider a one-electron moving on a Fermi, Pasta, Ulam disordered chain under effect of electron–phonon interaction and a Gaussian acoustic pulse pumping. We describe electronic dynamics using quantum mechanics formalism and the nonlinear atomic vibrations using standard classical physics. Solving numerical equations related to coupled quantum/classical behavior of this system, we study electronic propagation properties. Our calculations suggest that the acoustic pumping associated with the electron–lattice interaction promote a sub-diffusive electronic dynamics.