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YALTYCHENKO, Olga; KANAROVSKY, Evghenii; GORINCHOY, Natalia. Polarization effects in metal-carbon nanoclusters and dynamics of electron localization in external electric field. In: Materials Science and Condensed Matter Physics. Ediția a 9-a, 25-28 septembrie 2018, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2018, p. 214.
|Materials Science and Condensed Matter Physics
Ediția a 9-a, 2018
Conferința "International Conference on Materials Science and Condensed Matter Physics" |
Chișinău, Moldova, 25-28 septembrie 2018
The nonlinear and collective effects in the kinetic processes in the metal-carbon nanocluster‘s systems are very important for accounting both from the theoretical point of view and from the practical applications . The purpose of this work is to construct a dynamic model describing the electronic localization-delocalization, which can be extended for the nanoclusters (NC) with a large number of localization centers, using the example of a planar-square nanocluster (PSNC). In the represented model for describing the processes of localization and delocalization of a common electron in the NC of this type, in addition to its tunneling between the centers, an external low-frequency electric field, the electron polarization induced by this field at the PSNC centers and its ligand (carbon) shell, and electron-vibrational interaction are considered. The interaction of a common electron with the vibrational modes of the ligand environment at each of the centers of the tetrameric PSNC, and also the allowance for the polarization effects in such NC, leads to a nonlinear electron dynamics. As a result, in the model proposed here, the nonlinearity appears explicitly in the equations describing the electron subsystem, by the exclusion of the intracluster vibrational modes of the ligand environment of the PSNC centers and the polarization modes of the displacements of the collectivized electron density at each of the PSNC centers, taking into account its ligand environment. The numerical analysis of the solutions of the obtained system of equations relative to the amplitudes of the probability of detecting an electron at the centers of the NC for various values of the external and internal parameters of the system under study makes it possible to reveal the different regimes in the nonlinear dynamics of electron localization, as well as the conditions of switching between them. As shown in  (without taking into account the polarization effects), the following characteristic regimes of the dynamic localization of an electron can be realized in the tetrameric NC: 1) periodic regime of the switching of electron density between the first and third centers of the NC with a partial population of intermediate centers; 2) regime with the transparency effect of intermediate centers; 3) regime of the locking a common electron at one of the centers. It is important to note that the controlling role of the electric field makes it possible to realize both the regimes with electron localization and regimes with delocalization of an electron along the direction of action of the external electric field. Herewith, the variation of the frequency and amplitude of the field controls the duration of complete localization at the PSNC centers and switches it from the state with the localized electron into the state with a delocalized electron. Thus, in an external electric field, taking into account the polarization effects, the control of the regimes of electron density distribution in the PSNC (and not only for the NC of the type considered here) becomes more flexible, since on the one hand the nonlinear response of the system on the action of the field is taken into account, and on the other hand the increase in the number of tunable parameters facilitates the search for both new and previously detected regimes of electron localization in the NC. As a result, the given model, in application to the nanoclusters of this type, allows performing a detailed study of the governing role of the electric field, taking into account the contributions of the electron-vibrational interaction and the polarization effects, in the realization of the various electron localization regimes, thereby revealing the ways to switch between them.