Influence of external periodic electric field on electron localization and vibrational dynamics in trimer nanoclusters embedded in weak-structured materials
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YALTYCHENKO, Olga, KANAROVSKY, Evghenii. Influence of external periodic electric field on electron localization and vibrational dynamics in trimer nanoclusters embedded in weak-structured materials. In: Materials Science and Condensed Matter Physics, Ed. 7, 16-19 septembrie 2014, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2014, Editia 7, p. 224.
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Materials Science and Condensed Matter Physics
Editia 7, 2014
Conferința "Materials Science and Condensed Matter Physics"
7, Chișinău, Moldova, 16-19 septembrie 2014

Influence of external periodic electric field on electron localization and vibrational dynamics in trimer nanoclusters embedded in weak-structured materials


Pag. 224-224

Yaltychenko Olga, Kanarovsky Evghenii
 
Institute of Applied Physics, Academy of Sciences of Moldova
 
 
Disponibil în IBN: 11 martie 2019


Rezumat

In the given paper the capabilities to manage the certain physical characteristics of the composite material through the action on it by an external periodic electric field are studied. The simplest microscopic model for a composite material – the model of trinuclear nanocluster (NC) with one tunneling electron, embedded in a weak-structured nondissipative matrix is proposed. The theoretical description of the intracluster vibrational dynamics and degree of the localizationdelocalization of "extra" electron is based on the model Holstein's Hamiltonian supplemented by the terms cos( ) 0 dE t and m m i q Q . These terms are responsible, accordingly, for the interaction of NC electronic subsystem with external electric field and interaction of NC vibrational subsystem with vibrational system of a weak-structured matrix (for example, of the polymer or amorphous type). It is essential that the proposed theoretical approach involves the use of the time-dependent wave function written as the superposition of the electron-vibrational states in the coherent package form (as Davydov's ansatz). Such wave function is expressed through the time-dependent variational parameters: (t), (t), (t) j m m . They have a physical sense, respectively: 2 j – the electron population on the j-th center (j = 1,2,3), (t) m and (t) m – the quantum mechanical average values of the amplitudes of the coordinate and momentum for the m-th vibration m q (m = 1,2). Farther, using of Hamilton's canonical equations the system of differential equations is obtained. This system include 4 equations for values (t), (t) m m , that describe the behavior of the NC vibrational subsystem, and 3 equations for values (t) j , that describe the behavior of the NC electronic subsystem. These differential equations include both the internal and external model parameters. The internal parameters 0 t , m g and are, accordingly, – the parameter of the electron tunneling between the trimer centers, the constant of the electron-phonon interaction for the m-th intracluster vibrational mode and the energy detuning, which characterizes a nonequivalence of the intermediate trimer center. Next, the vibrational degrees of freedom of the matrix are eliminated, assuming that the external mode i Q much slower than intracluster modes. As a result, the intracluster modes are directly connected that significantly affects on the energy exchange between them. Eventually, the numerical solution of the obtained system of differential equations with account of initial conditions is performed for the different values of model parameters. From these calculations follows that for the electron populations of the NC centers together with very fast oscillations in time there are also the slow oscillations of their average values. It should be emphasized that by a selection of the model parameters can lead a nanocluster in state with certain distribution of the electron density on its centers, furthermore, by changing one or more parameters the redistribution of electron density can be performed (i.e., the switching between the different distribution regimes). Thus, if at the fabrication of the composite film containing the trimeric nanoclusters to achieve their certain orientation within the matrix, for example, using the constant external electric or magnetic fields, or other orienting effects, it is possible to get a composite film with controlled polarization properties by the action of an external periodic electric field on it. That is interesting for the microand optoelectronics applications. Furthermore, it is important to note that a control of the physical characteristics of the nanoclusters highly demanded in the biotechnological applications due to a possibility of influence on their catalytic and biological activity.