Igor Lukačević

Antimonene: a monolayer material for ultraviolet optical nanodevices

Two-dimensional materials draw further attention because of their superior properties applicable in novel technologies. We have calculated the optical properties of α and β allotropes of antimonene monolayers. Their dielectric matrices have been calculated within the random phase approximation (RPA) using density functional theory. We have calculated dielectric functions, absorption coefficients, refractive indices, electron energy loss spectra and optical reflectivities in the energy range between 0 and 21 eV. Our simulations predict that absorption process starts in the infrared, but peaks in the ultraviolet region. The values of refractive index are 2.3 (α-Sb) and 1.5 (β-Sb) at the zero energy limit and scale up to 3.6 in the ultraviolet region. Reflection rises up to 86% at the UV energies, where antimonene behaves like a metal regarding the incident electromagnetic radiation. Our calculations show that antimonene is suitable as a material for the microelectronic and optoelectronic nanodevices and solar cell applications, as well as for new optical applications using various light emission, detection, modulation and manipulation functions.

Indiene 2D monolayer: a new nanoelectronic material

One atom thick monolayer nanostructures consisting of group III, IV and V elements are drawing ever more attention for their extraordinary electronic properties. Through first principles calculations, we systematically investigate structural and electronic properties of the corresponding indium monolayers in three different allotropic forms: planar, puckered and buckled. Our study shows that the planar and buckled allotropes are stable and show metallic and semiconducting behavior, respectively. Their stability and electronic properties cannot be easily correlated to those of similar elemental monolayer structures. The van Hove singularity is observed in the electronic density of states which could lead to an increase in the electronic conductivity, opening paths to new electronic applications. Strain engineering is applied in order to determine the changes in the electronic behavior and band gap properties. The planar allotrope remains metallic under both compressive and tensile strain, while the buckled allotrope changes from an indirect semiconductor to a metal. Our study demonstrates that the indiene nanostructures possess diverse electronic properties, tunable by strain engineering, which have potential applications in nanoelectronics and for nanodevices.

First step to investigate nature of electronic states and transport in flower-like MoS2: Combining experimental studies with computational calculations.

In the present paper, the nature of electronic states and transport properties of nanostructured flower-like molybdenum disulphide grown by hydrothermal route has been studied. The band structure, electronic nature of charge, thermodynamics and the limit of phonon scattering through density functional theory (DFT) has also been studied. The band tail states, dynamics of trap states and transport of carriers was investigated through intensive impedance spectroscopy analysis. The direct fingerprint of density and band tail state is analyzed from the capacitance plot as capacitance reflects the capability of a semiconductor to accept or release the charge carriers with a corresponding change in its Fermi potential levels. A recently introduced infrared photo-carrier radiometry and density functional perturbation theory (DFPT) techniques have been used to determine the temperature dependence of carrier mobility in flower type-MoS2. The present study illustrates that a large amount of trapped charges leads to an underestimation of the measured effective mobility and the potential of the material. Thus, a continuous engineering effort is required to improve the quality of fabricated nanostructures for its potential applications.

Efficiency of colored modified box traps for sampling of tabanids

The efficiency of ten differently colored modified box traps for collecting tabanids was studied in the Monjoroš Forest in eastern Croatia. A total of 5,436 specimens belonging to 16 species of tabanids grouped into six genera were collected. The genus Tabanus was the most represented with 98% of all collected tabanids. Tabanus bromius comprised 90% of tabanids collected, and was the most abundant species collected in all box traps. The majority of tabanids (74%) were collected from black, brown, bordeaux, red, and blue traps (dark group), whereas 26% were collected from green, light violet, white, orange, and yellow traps (light group). The black modified trap was the most successful and collected 20% of all collected tabanids, whereas the yellow trap was the least effective with 1%. The number of collected specimens of species T. bromius differed significantly between the dark and light group of traps. Traps with lower reflectance from green color collected 77% of T. bromius. The most species of tabanids (12) was collected in the brown trap, whereas the least number of species (6) was collected in the yellow trap.

Pressure-induced structural phase transition and elastic properties in rare earth CeBi and LaBi

A comprehensive first principles study of structural, elastic, electronic and phonon properties of rare-earth CeBi and LaBi is reported within the density functional theory scheme. The ground state properties such as lattice constant, elastic constants, bulk modulus, and finally the phase transition and lattice dynamical properties of rare-earth CeBi and LaBi of rocksalt (B1) and CsCl (B2) structures are determined. The electron band structures for the two phases of both rare-earth crystals are presented. We have calculated phonon dispersion curve, showing that all phonon modes in phonon dispersion curves of B1 phase in CeBi and LaBi are positive, which indicates a stable phase for this structure.

Ab-initio approach to IrO2 polymorphs – properties at high pressures

The present paper reports the structural and lattice dynamical study for iridium dioxide (IrO2) at ambient and higher pressure conditions up to 60 GPa. Total energy calculations are carried out using first principle density functional theory. The ground state properties like lattice constant, bulk modulus are calculated and are in good agreement with theoretically and experimentally reported values. The band structure calculations confirm the metallic character of IrO2. The analysis of calculated phonon dispersion curves illuminates the structural systematic and the nature of phase transitions under the influence of pressure.

The role of pressure in elastic properties of cerium

Cerium 4f electrons are peculiar in being spatially localized with a radial extent much smaller than that of 5s and 5p semicore states, yet having an energy in the region of valence 6s and 5f electrons. Two phases, α and γ, of cerium are under debate in terms of different properties like elastic properties or phase transition properties. The mechanical and elastic properties of cerium have generated substantial interest over the years both experimentally and theoretically. Theoretical studies, concerned with the lattice dynamics, which may be of use, as it is expected from the electron-phonon interaction, and plays a significant role during the γ → α transition, are very limited. The aim of the present work is to study the behavior of lattice dynamics and elastic constants under increasing pressure using first-principles methods within linear response approach for the face-centered cubic (fcc) γ-cerium and shed some light on the interrelationship among the elasticity and phonons and understand the role of phonons in the phase transition. Our calculations reproduce zero pressure lattice dynamical and elastic properties of cerium with a very good precision.