Dynamic Symmetry in Dozy-Chaos Mechanics

All kinds of dynamic symmetries in dozy-chaos (quantum-classical) mechanics (Egorov, V.V. Challenges 2020, 11, 16; Egorov, V.V. Heliyon Physics 2019, 5, e02579), which takes into account the chaotic dynamics of the joint electron-nuclear motion in the transient state of molecular “quantum” transitions, are discussed. The reason for the emergence of chaotic dynamics is associated with a certain new property of electrons, consisting in the provocation of chaos (dozy chaos) in a transient state, which appears in them as a result of the binding of atoms by electrons into molecules and condensed matter and which provides the possibility of reorganizing a very heavy nuclear subsystem as a result of transitions of light electrons. Formally, dozy chaos is introduced into the theory of molecular “quantum” transitions to eliminate the significant singularity in the transition rates, which is present in the theory when it goes beyond the Born–Oppenheimer adiabatic approximation and the Franck–Condon principle. Dozy chaos is introduced by replacing the infinitesimal imaginary addition in the energy denominator of the full Green’s function of the electron-nuclear system with a finite value, which is called the dozy-chaos energy γ. The result for the transition-rate constant does not change when the sign of γ is changed. Other dynamic symmetries appearing in theory are associated with the emergence of dynamic organization in electronic-vibrational transitions, in particular with the emergence of an electron-nuclear-reorganization resonance (the so-called Egorov resonance) and its antisymmetric (chaotic) “twin”, with direct and reverse transitions, as well as with different values of the electron–phonon interaction in the initial and final states of the system. All these dynamic symmetries are investigated using the simplest example of quantum-classical mechanics, namely, the example of quantum-classical mechanics of elementary electron-charge transfers in condensed media.

Dynamics of Silicon Nanostructures Under Laser Irradiation Studied Quantum Mechanically

ABSTRACTThis study is motivated by recent applications of ultra-short laser pulses to the manipulation of structures on the atomic scale. It describes the energies and the time-scale needed to induce and to observe such changes. The structures adopted to this purpose are taken from the field of silicon nanotechnology and consist on monotaomic wires and small clusters of a columnar shape. These last ones are covered on both sides with an aluminum overlayer and can be regarded as the finite-size analogous of macroscopic electronic devices. The effect of laser is simply described as an increase of the kinetic energy in the nuclear subsystem. The calculations are based on real-time, real-space implementation of the semiempirical Hartree-Fock theory. The results show the occurrence of phenomena similar to recristallization and melting in the bulk and illustrate the dependence of these effects on the energy input and on the cluster size and composition.