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Full-Text Articles in Physics
Electro-Optical Effect Of 4-N-Alkyl-Sulfanyl-4' Isothiocyanate-Biphenyl Liquid Crystal Homologous Series Under Terahertz Frequency: A Theoretical Approach, Yogesh Kumar, Narinder Kumar
Electro-Optical Effect Of 4-N-Alkyl-Sulfanyl-4' Isothiocyanate-Biphenyl Liquid Crystal Homologous Series Under Terahertz Frequency: A Theoretical Approach, Yogesh Kumar, Narinder Kumar
Makara Journal of Science
This work presented the electro-optical effect of the homologous series 4-n-alkyl-sulfanyl-4'-isothiocyanate-biphenyl (N1SC13H8-SH2n+1Cn) under an electric field with terahertz (THz) frequency. The increase in alkyl sulfanyl chain length reduces the birefringence but increases the order parameter in THz frequency. An inverse relationship exists between the birefringence and order parameter. Meanwhile, the increase in alkyl sulfanyl chain length increases the refractive index with an even–odd effect. Birefringence, refractive index, order parameter, and director angle show an even–odd effect in the THz frequency range. The calculation is performed between 1 and 1,200 THz frequency. The isothiocyanate stretching corresponding to …
Dft-Based Study Of Electric Field Effect On The Polarizability Of Three Ringed Nematic Liquid Crystal Molecules, Pranav Upadhyay, Mirtunjai Mishra, Ankur Trivedi, Jitendra Kumar, Asheesh Kumar, Devesh Kumar
Dft-Based Study Of Electric Field Effect On The Polarizability Of Three Ringed Nematic Liquid Crystal Molecules, Pranav Upadhyay, Mirtunjai Mishra, Ankur Trivedi, Jitendra Kumar, Asheesh Kumar, Devesh Kumar
Makara Journal of Science
Owing to its successful application to complex molecular systems, computational density functional theory (DFT) has been used to study the effect of an electric field on the molecular polarizability and HOMO–LUMO gap of 1-phenyl-4-{2-[(1s,4r)-4-pentylcyclohexyl]ethyl}benzene (1) and its fluoro-, chloro-, and cyano- derivatives, namely, 1-fluoro-4-(4-{2-[(1s,4r)-4-pentylcyclohexyl]ethyl}phenyl)benzene (2), 1-chloro-4-(4-{2-[(1s,4r)-4-pentylcyclohexyl]ethyl}phenyl)benzene (3), and 4-(4-{2-[(1s,4r)-4-pentylcyclohexyl]ethyl}phenyl)benzonitrile (4). These molecules belong to the family of nematic liquid crystals with three rings: two benzene and one cyclohexane. Furthermore, two DFT approaches, namely, B3LYP and M062X, have been used to examine the results obtained. This study reveals a remarkable feature: the polarizability of these molecules follows nearly a step function …
Stable Anisotropic Single-Layer Of Rete$_2$: A First Principles Prediction, Mehmet Yağmurcukardeş
Stable Anisotropic Single-Layer Of Rete$_2$: A First Principles Prediction, Mehmet Yağmurcukardeş
Turkish Journal of Physics
In order to investigate the structural, vibrational, electronic, and mechanical features of single-layer ReTe$_2$ first-principles calculations are performed. Dynamical stability analyses reveal that single-layer ReTe$_2$ crystallize in a distorted phase while its 1H and 1T phases are dynamically unstable. Raman spectrum calculations show that single-layer distorted phase of ReTe$_2$ exhibits 18 Raman peaks similar to those of ReS$_2$ and ReSe$_2$. Electronically, single-layer ReTe$_2$ is shown to be an indirect gap semiconductor with a suitable band gap for optoelectronic applications. In addition, it is found that the formation of Re-units in the crystal induces anisotropic mechanical parameters. The in-plane stiffness and …
Ab Initio Atomistic Thermodynamics Modeling Of Adsorption Of Oxygen On Goldand Gold-Silver Surfaces, Mehmet Gökhan Şensoy
Ab Initio Atomistic Thermodynamics Modeling Of Adsorption Of Oxygen On Goldand Gold-Silver Surfaces, Mehmet Gökhan Şensoy
Turkish Journal of Physics
A theoretical study of oxygen adsorption on gold and gold-silver surfaces by means of density functional theory (DFT) calculations with an atomistic thermodynamic model is performed. The (111) and (211) facets of gold and gold-silver alloy surfaces are considered, and their stabilization is discussed upon adsorption of oxygen depending on O and Ag coverage. The details of how the DFT-based atomistic thermodynamic model can apply to the transition metal surface are also presented in this work.
Two-Dimensional Ti2c Monolayer (Mxene): Surface Functionalization, Inducedmetal, Semiconductor Transition, Berna Akgenc
Two-Dimensional Ti2c Monolayer (Mxene): Surface Functionalization, Inducedmetal, Semiconductor Transition, Berna Akgenc
Turkish Journal of Physics
Recently, two-dimensional (2D) transition metal carbides and nitrides known as MXenes, have gained a lot of attention because of their tunable electronic and magnetic properties depending on surface functionalization. In the present work, the structural, electronic, and magnetic properties of both T and H phases of bare Ti2C and fully surface terminated Ti2 CT2 (T = -F, = O, -OH) are calculated using a set of first principles calculations. The ground state structures of Ti2 CT2 are computed in two and four different configurations for both H and T phases, respectively. We demonstrate that while H phase of Ti2C exhibits …
A Comparative Study Of The Electronic Properties Of Aluminum Nitride Compounds, Rezek Mohammad, Şenay Katircioğlu
A Comparative Study Of The Electronic Properties Of Aluminum Nitride Compounds, Rezek Mohammad, Şenay Katircioğlu
Turkish Journal of Physics
Electronic properties of aluminum nitride in wurtzite, zinc-blende, and rock-salt phases are investigated by a full potential-linearized augmented plane waves method based on density functional theory within standard local density approximation and its four improved versions. Local density approximation corrected by the generalized gradient functional of Perdew-Wang-Engel-Vosko is found to be more successful than the other generalized gradient functional approximations considered in this work for providing reasonable lattice constants, energy gaps, effective electron and hole masses, and optical features for AlN phases. Although local density approximation corrected by modified Becke-Johnson potential underestimates the static dielectric constants, it provides the largest …
A Study On Si And P Doped H-Bn Sheets: Dft Calculations, Hati̇ce Kökten, Şaki̇r Erkoç
A Study On Si And P Doped H-Bn Sheets: Dft Calculations, Hati̇ce Kökten, Şaki̇r Erkoç
Turkish Journal of Physics
Structural properties and energetics of silicon and phosphorus doped hexagonal boron nitride sheets were investigated by performing density functional theory calculations. The dopant atoms were substituted in a neutral charge state at either the B or the N site in the system as an impurity. All the systems under consideration were fully optimized. A systematic study was performed to see the effect of cell size on the calculated quantities, such as bond length, charge transfer, and defect formation energies. It was found that both silicon and phosphorus atom substitutions cause the bond lengths to increase with respect to the pristine …
Vibrational Analysis Of Flavone, Yusuf Erdoğdu, Ozan Ünsalan, M. Tahi̇r Güllüoğlu
Vibrational Analysis Of Flavone, Yusuf Erdoğdu, Ozan Ünsalan, M. Tahi̇r Güllüoğlu
Turkish Journal of Physics
In this study, the experimental and theoretical study on the structures and vibrations of flavone are presented. FT-IR and FT-Raman spectra of the molecule have been recorded in the 400-4000 cm^{-1} region and the 5-3500 cm^{-1} region, respectively. The molecular geometry and vibrational frequencies of flavone in the ground state have been calculated by using Density Functional method (B3LYP) in conjunction with 6-311++G(d,p) and 6-31++G(d) as basis sets.
First Principles Modeling Of Nanostructures, Serdar Öğüt
First Principles Modeling Of Nanostructures, Serdar Öğüt
Turkish Journal of Physics
Among the various theoretical tools for investigating microscopic material properties, ab initio (first principles) methods based on density functional theory and pseudopotentials have had a very good track record over the last two decades in terms of accuracy, reliability, and efficiency. The application of these methods to nanostructures to investigate their structural, electronic, and optical properties has, however, not been quite straightforward due to the large computational demand and new physics inherent in the nanometer and sub-nanometer size region. One particularly useful extension to overcome the computational demand imposed by localized nanostructures has been the introduction of methods based on …