Petreska, Irina

Preferred name

Petreska, Irina

Official Name

Petreska, Irina

Main Affiliation

irina.petreska@pmf.ukim.mk

Now showing 1 - 10 of 14

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The time-dependent Schrödinger equation in three dimensions under geometric constraints
(AIP Publishing, 2019-03)
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de Castro, Antonio S. M.
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Sandev, Trifce
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Lenzi, Ervin K.
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Comb-like geometric constraints leading to emergence of the time-fractional Schrödinger equation
(World Scientific Pub Co Pte Lt, 2021-01-29)
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Sandev, Trifce
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Lenzi, Ervin Kaminski
<jats:p> This paper presents an overview over several examples, where the comb-like geometric constraints lead to emergence of the time-fractional Schrödinger equation. Motion of a quantum object on a comb structure is modeled by a suitable modification of the kinetic energy operator, obtained by insertion of the Dirac delta function in the Laplacian. First, we consider motion of a free particle on two- and three-dimensional comb structures, and then we extend the study to the interacting cases. A general form of a nonlocal term, which describes the interactions of the particle with the medium, is included in the Hamiltonian, and later on, the cases of constant and Dirac delta potentials are analyzed. At the end, we discuss the case of non-integer dimensions, considering separately the case of fractal dimension between one and two, and the case of fractal dimension between two and three. All these examples show that even though we are starting with the standard time-dependent Schrödinger equation on a comb, the time-fractional equation for the Green’s functions appears, due to these specific geometric constraints. </jats:p>
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Axially symmetrical molecules in electric and magnetic fields: energy spectrum and selection rules
(Walter de Gruyter GmbH, 2013-01-01)
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Sandev, Trifce
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Nedelkoski, Zlatko
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Pejov, Ljupco
<jats:title>Abstract</jats:title><jats:p>In this paper we investigate the effects of external electric and magnetic fields on a three-dimensional harmonic oscillator with axial symmetry. The energy spectrum of such a system is non-degenerate due to the presence of the magnetic field. The degeneracy of the energy spectrum in the absence of a magnetic field is discussed. The influence of electric and magnetic fields, as well as the frequencies of the oscillator on the probability distribution function is analyzed. Optical transition probabilities are examined by deriving the selection rules in dipole approximation for the quantum numbers n p, m l and n z. Employing stationary perturbation theory, the effects of deformations of the potential energy function on the oscillatory states are analyzed. Such models have been used in literature in analysis of spectra of axially symmetrical molecules and cylindrical quantum dots.</jats:p>
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Designing field-controllable graphene-dot-graphene single molecule switches: A quantum-theoretical proof-of-concept under realistic operating conditions
(AIP Publishing, 2015-12-28)
Pejov, Ljupčo
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Kocarev, Ljupčo
A theoretical proof of the concept that a particularly designed graphene-based moletronics device, constituted by two semi-infinite graphene subunits, acting as source and drain electrodes, and a central benzenoid ring rotator (a "quantum dot"), could act as a field-controllable molecular switch is outlined and analyzed with the density functional theory approach. Besides the ideal (0 K) case, we also consider the operation of such a device under realistic operating (i.e., finite-temperature) conditions. An in-depth insight into the physics behind device controllability by an external field was gained by thorough analyses of the torsional potential of the dot under various conditions (absence or presence of an external gating field with varying strength), computing the torsional correlation time and transition probabilities within the Bloembergen-Purcell-Pound formalism. Both classical and quantum mechanical tunneling contributions to the intramolecular rotation were considered in the model. The main idea that we put forward in the present study is that intramolecular rotors can be controlled by the gating field even in cases when these groups do not possess a permanent dipole moment (as in cases considered previously by us [I. Petreska et al., J. Chem. Phys. 134, 014708-1-014708-12 (2011)] and also by other groups [P. E. Kornilovitch et al., Phys. Rev. B 66, 245413-1-245413-7 (2002)]). Consequently, one can control the molecular switching properties by an external electrostatic field utilizing even nonpolar intramolecular rotors (i.e., in a more general case than those considered so far). Molecular admittance of the currently considered graphene-based molecular switch under various conditions is analyzed employing non-equilibrium Green's function formalism, as well as by analysis of frontier molecular orbitals' behavior.
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Fractional Schrödinger equation and anomalous relaxation: Nonlocal terms and delta potentials
(World Scientific Pub Co Pte Lt, 2021-02-18)
Lenzi, Ervin K.
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Evangelista, Luiz R.
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Zola, Rafael S.
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Sandev, Trifce
<jats:p> We review and extend some results for the fractional Schrödinger equation by considering nonlocal terms or potential given in terms of delta functions. For each case, we have obtained the solution in terms of the Green function approach. </jats:p>
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Tunneling of electrons via rotor–stator molecular interfaces: Combined ab initio and model study
(Elsevier BV, 2016-07)
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Ohanesjan, Vladimir
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Pejov, Ljupčo
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Kocarev, Ljupčo
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Constrained quantum motion in δ-potential and application of a generalized integral operator
(Elsevier BV, 2019-09)
Sandev, Trifce
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Lenzi, Ervin K.
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BIASING FIELD EFFECTS ON ELECTRONIC PROPERTIES IN HALOGENATED PHENYLENE ETHYNYLENE OLIGOMERS
(Macedonian Academy of Sciences and Arts, 2017-03-27)
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Pejov, Ljupčo
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Kocarev, Ljupčo
<jats:p>In this paper results from ab initio simulations of the electronic structure properties of a class of halogenated phenylene ethynylene oligomers (OPE) are presented. These molecular species are investigated because of their suitable properties for application as single-molecule switches in the future emerging molecular electronic devices. Combined Hartree-Fock and Density Functional Theory approach is applied to investigate the biasing field effects on the relevant electronic properties, such as potential energy of the ground states, potential barrier height, localization of frontier molecular orbitals and the HOMO-LUMO gap. Special attention is also paid on the effects of substitution of the hydrogen atoms in the central phenylene ring of basic OPE molecule with halogen atoms. The analyses of the obtained results undoubtedly show that the biasing field has a strong impact on the potential barrier height, transition probabilities and band gap. Halogenation of the central phenylene ring does not have such a strong influence on the aforementioned properties, but it could be a useful way for fine tuning of some of the properties, especially the potential barrier height, enabling control of the torsional stochastic switching, inherent for the studied species.</jats:p>
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Magnetic properties of electrons confined in an anisotropic cylindrical potential
(Elsevier BV, 2014-11)
Nedelkoski, Zlatko
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Exploring the possibilities to control the molecular switching properties and dynamics: A field-switchable rotor-stator molecular system
(AIP Publishing, 2011-01-07)
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Pejov, Ljupco
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Kocarev, Ljupco
A bistable, dipolar stator-rotor molecular system-candidate for molecular electronics is investigated. We demonstrate that it is possible to control the intramolecular torsional states and dynamics in this system by applying an appropriate additional electric field (instead of biasing one), achieving fine tuning and modulation of the relevant properties. The electric field effects on the quantities responsible for torsional dynamics (potential energy surface, potential barrier height, quantum and classical transition probabilities, correlation time, HOMO-LUMO gap) are studied from first principles. Our results indicate that it is possible to artificially stabilize the metastable conformational state of the studied molecule. The importance of this is evident, as the current-voltage characteristics of the metastable state are clearly distinguishable from the current-voltage characteristics of the two stable states. We report for the first time exact calculations related to the possibilities to control the thermally induced stochastic switching, and reduce the noise in a practical application. Thus, we believe that the molecule studied in this paper could operate as a field-switchable molecular device under real conditions.

Petreska, Irina

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