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In the present work, the structural, electronic and mechanical properties of Na2IrO3 and Li2IrO3 have been investigated by means of first principles calculations. The spin polarized generalized gradient approximation has been used for modeling exchange-correlation effects. The structural optimization of these compounds has been performed by using VASP-code, and the lattice parameters and magnetic moments have been calculated. From our calculation, it has been determined that X2IrO3 (X = Na, Li) compounds for both spin up and spin down states are indirect wide gap semiconductor in nature. Considering the spin states from the electronic band structure and density of the state (DOS) of the Na (Li)2IrO3 compounds, it has been identified that Eg=1.824 (2.315) eV for spin up and Eg=1.558 (2.019) eV for spin down. The second-order elastic constants have been calculated, and the other related quantities have also been estimated in the present work.

In the present paper, we have investigated the electronic structure of some sillenites - Bi12MO20 (M = Ti, Ge, and Si) compounds based on the density functional theory. The mechanical and optical properties of Bi12MO20 have also been computed. The second-order elastic constants have been calculated, and the other related quantities have also been estimated in the present work. The band gap trend in Bi12MO20 can be understood from the nature of their electronic structures. The obtained electronic band structure for all Bi12MO20 compounds is semiconductor in nature. Similar to other oxides, there is a pronounced hybridization of electronic states between M-site cations and anions in Bi12MO20. Based on the obtained electronic structures, we further calculate the frequency-dependent dielectric function and other optical functions.

In this work, we present an investigation of the optical properties and band structures for the photonic crystal structures (PCs) based on Sn2P2X6: X = S, Se) with Fibonacci superlattices. The optical properties of PCs can be tuned by varying structure parameters such as the lengths of poled domains, filling factor, and dispersion relation. In our simulation, we employed the finite-difference time domain technique and the plane wave expansion method, which implies the solution of Maxwell equations with centered finite-difference expressions for the space and time derivatives.

The goal of the work presented in this investigation is to achieve the efficient parametric interaction of narrow beams (in particular second harmonic generation) using a nonlinear (ferroelectric-LiTaO3) photonic crystal tuned to self-collimation (nondiffractive) regimes. A numerical study of second harmonic generation (SHG) in one-dimensional nonlinear photonic crystals based on a full nonlinear system of equations, implemented by a combination of the method of finite elements and fixed-point iterations, is reported. This model is derived from a nonlinear system of Maxwell’s equations that partly overcomes the known shortcoming of some existing models that rely on the undepleted pump approximation. We derive a general solution of SHG in one-dimensional nonlinear photonic crystals structures. Numerical simulations also show that the conversion efficiency of SHG can be significantly enhanced when the frequencies of the fundamental wave are located at the photonic band edges or are assigned to the designed defect states.

In present paper, the structural, mechanical, and electronic properties of the Sn2P2S6 compound under different pressures by the density functional methods in the generalized gradient approximation have been examined in the ferroelectric (Pc) and paraelectric (P2_1/c) phases. The lattice parameters, mechanical properties, electronic bands structures and partial density of states for both phases are presented and analyzed. The nonlinear optical properties and electro-optic effects of Sn2P2S6-Pc have been studied by the density functional theory in the local density approximation. Our structural estimation and some other results are in agreement with the available experimental and theoretical data. We present calculations of the frequency-dependent complex dielectric function (ω) and the second harmonic generation response coefficient χ(2) (−2ω, ω, ω) over a large frequency range. The electronic linear electro-optic susceptibility χ(2) (−ω, ω, 0) is also evaluated below the band gap. These results are based on a series of the LDA calculation. The results for χ(2) (−ω, ω, 0) are in agreement with the experiment below the band gap and those for χ(2) (−ω, ω, 0) are compared with the experimental data where available.

In this study, the band structure and transmission spectra in multiferroic based Sierpinski-carpet phononic crystal are investigated based on finite element simulation. In order to obtain the band structure of the phononic crystal (PnC), the Floquet periodicity conditions were applied to the sides of unit cell. The square lattice PnC consists of various piezoelectric inclusion in a rubber matrix with circular and triangular cross section.

In the present paper we have investigated the electronic structure of some orthorhombic A(3)X(2)S(7) (X = Ti, Zr, and Hf) compounds based on the density functional theory. Then we extend the RuddlesdenPopper (RP) A(3)X(2)S(7) sulfides and examine how ferroelectricity is induced by coupled octahedral rotation modes. The mechanical and optical properties have also been computed. The second-order elastic constants have been calculated, and the other related quantities have also been estimated in the present work. The band gap trend in A(3)X(2)S(7) can be understood from the nature of their electronic structures. The obtained electronic band structure for Ba3Hf2S7 and Ba3Hf2S7 compounds are semiconductor in nature, and the Ba3Hf2S7 compound is also semi-metal. Similar to ferroelectric oxides, there is a pronounced hybridization of electronic states between X-site cations and anions in A(3)X(2)S(7). Based on the obtained electronic structures, we further calculate the frequency-dependent dielectric function and other optical functions in different phases.

In this work, we study the band gap properties of a two-dimensional phononic crystal composed of a hexagonal cavity inside a circular enclosure embedded in a homogeneous matrix. A simple two-dimensional structure with a cavity that is modeled with an opening in one side that allows air to enter was studied theoretically using the finite element method (FEM). The properties of acoustic wave propagation in a phononic crystal consisting of periodic inclusions with a cavity placed in an air host material are analyzed. The phononic crystal dispersion relations, transmission loss spectrum, and displacement fields of the eigenmodes of this phononic crystal are investigated. The pressure field distribution inside the domain is solved parametrically through a two-dimensional acoustic wave equation in the horizontal plane as a function of frequency. We have found that several complete band gaps with a variable bandwidth exist for the acoustic waves of longitudinal polarization.

The electronic, mechanical, and optical properties of the Kagome staircase compounds, Mn3V2O8 and Ni3V2O8, have been investigated using the VASP (Vienna ab-initio Simulation Program) that was developed within the density functional theory (DFT). The spin polarized generalized gradient approximation has been used for modeling exchange-correlation effects. The electronic band structures for both compounds and total and partial density of states corresponding to these band structures have been calculated. Spin up (spin down) Eg values for Mn3V2O8 and Ni3V2O8 compounds are 0.77 eV indirect (3.18 direct) and 1.58 eV indirect (0.62 eV) direct, respectively. The band gaps of both compound is in the d-d character. Bulk modulus, shear modulus, Young's modulus, Poisson's ratio, anisotropic factors, sound velocity, and Debye temperature were calculated and interpreted.

Bu çalışmada, bir kareörgülü hava matrisinde yer alan kare şekilli saçılardan oluşan iki boyutlufononik kristallerin bant yapısı çalışıldı. Bant yapısı hesaplamaları için, birhava matrisindeki kare LiNbO3 çubuklarından oluşan iki boyutlu birfononik kristal dikkate alındı. Kare çubukların yönelimlerinin akustik bantaralıkları üzerindeki etkisi, iletim kaybı spektrumları, basınç alanı haritasıve dağılım ilişkileri sonlu elemanlar yöntemi ve Bloch teoremi kullanılarakhesaplandı. Bu yapı için maksimum bant aralığı 45° dönme açısında bulundu.Sayısal sonuçlar, bant aralıklarının kare çubukların dönüş açısını değiştirerekayarlanabileceğini göstermektedir.

In the present work the acoustic band structure of a two-dimensional phononic crystal containing an organic ferroelectric (PVDF- polyvinylidene fluoride) and muliferroic material (LiVCuO4) were investigated by the plane-wave-expansion method. A two-dimensional PC with square lattices composed of LiVCuO4 cylindrical rods embedded in the PVDF matrix are studied to find the existence of stop bands for the waves of certain energy. This phononic bandgap - forbidden frequency range - allows sound to be controlled in many useful ways in structures that can act as sonic filters, waveguides or resonant cavities. Phononic band diagram omega = omega(k) for a 2D PC, in which non-dimensional frequencies omega a/2 pi c (c-velocity of wave) were plotted versus the wavevector k along the Gamma-X-M-Gamma path in the square Brillouin zone show four stop bands in the frequency range 0.01-8.0 kHz. The ferroelectric properties of PVDF and unusual properties of multiferroic LiVCuO4 give us the ability to control the wave propagation through the PC in over a wide frequency range.

We present band structure results for elastic waves in periodic composite materials consisting of a spiral scatterer shape embedded in a uniform silicon matrix. The material of the scatterer is tungsten as a high density material. The phononic band structure of two-dimensional solid phononic crystal is studied numerically by finite element method to obtain dispersion relations. We find full band gaps at relatively low frequencies for a low filling ratio. Due to spatial inhomogeneity, the unique structural characteristics of the spiral structure lead to localized modes. Hence, the proposed model geometry introduces a phononic crystal to cover a wide range of stopbands starting from low frequencies. The results could give a possibility to design effective filters for the low frequency range.

In this report, we present an investigation of the optical properties and band structure calculations for the photonic structures based on the multiferroic materials- BaMnF4. We calculate the photonic bands and optical properties of BaMnF4/LiNbO3 based photonic crystal. We study the photonic band gap and optical properties of the photonic structures, numerically analyzed in the IR frequency region by using the FDTD method for various incidence angles, number of periods in the PC and the nature/geometry of the materials. This work is supported by the projects DPT-HAMIT. One of the authors (Ekmel Ozbay) also acknowledges partial support from the Turkish Academy of Sciences.

In the present work, the acoustic band structure of a two-dimensional (2D) phononic crystal containing a multiferroic and liquid were investigated by the plane-wave-expansion method. 2D PnC with triangular and honeycomb lattices composed of LiCu2O4 cylindrical rods embedded in the seawater matrix are studied to find the existence of stop bands for the waves of certain energy. Phononic band diagram ω=ω(k) for a 2D PC, in which nondimensional frequencies ωa/2πc (c-velocity of wave) were plotted versus the wavevector k along the г-X-M-г path in the Brillouin zone show few stop bands in the frequency range between 10 and 110 kHz.

We present the ab initio study the electronic, mechanical and structural properties of BaMnF4. We duscuss the trends in the electronic and mechanical properties of BaMnF4 under pressure up to 80 GPa. BaMnF4 belongs to the family of BaMF4-type fluorides (M = Mn, Fe, Co, Ni, Mg, Zn) which share the same orthorhombic structure. The main focus of this study is to elaborate the changes brought about in the electronic and the structural properties by applied pressure. The calculated lattice parameters have been in agreement with the available experimental and theoretical value. Band gap of BaMnF4 in our calculation is about 2.0 eV, separating the empty upper-Hubbard t2g bands and occupied lower-Hubbard eg bands. The total and partial DOS corresponding to the electronic band structure are calculated. Comparative analysis of the results of these calculations shows that the band-gap energy of BaMnF4 decreases with increasing pressure and has a minima value at a critical pressure (appr. 65 GPa), after which it increases again. Some fundamental physical parameters such as elastic constants, bulk modulus, Poisson’s ratio, sound velocities and Debye temperature were calculated and interpreted, too.

The authors are grateful to the ABINIT group for the ABINIT project that we used in our computations. The nonlinear optical properties and electro-optic effects of some oxygen-octahedra ferroelectrics are studied by the density functional theory (DFT) in the local density approximation (LDA) expressions based on first principle calculations without the scissor approximation. We present calculations of the frequency- dependent complex dielectric function (?) and the second harmonic generation response coefficient ?(2)(-2?, ?, ?) over a large frequency range in tetragonal and rhombohedral phases. The electronic linear electro-optic susceptibility ?(2)(-?, ?, 0) is also evaluated below the band gap. These results are based on a series of the LDA calculation using DFT. The results for ?(2)(-?, ?, 0) are in agreement with the experiment below the band gap and those for ?(2)(-2?, ?, ?) are compared with the experimental data where available. This work is supported by the projects DPT-HAMIT, DPT-FOTON, and NATO-SET-193 and TUBITAK under the project nos., 113E331, 109A015, and 109E301. One of the authors (Ekmel Ozbay) also acknowledges partial support fromthe Turkish Academy of Sciences.

We have performed a first principles study of the structural, elastic and electronic properties of orthorhombic SnS and GeS compounds using the density functional theory within the local density approximation. The second-order elastic constants have been calculated, and the other related quantities such as the Young's modulus, shear modulus, Poisson's ratio, anisotropy factor, sound velocities, Debye temperature, and hardness have also been estimated in the present work. All of the calculated modulus and Poisson's ratio for SnS were less than the same parameters for GeS. Our calculations have discovered the large anisotropy of elastic parameters in the (100) and (010)-planes for both compounds. The band structures of orthorhombic SnS and GeS have been calculated along high symmetry directions in the first Brillouin zone (BZ). The calculation results for the band gap of Sn(Ge)S gave Eg = 0.256 eV (0.852 eV) and has an indirect character for an interband transition. The real and imaginary parts of dielectric functions and (by using these results) the optical constant such as energy-loss function, the effective number of valance electrons and the effective optical dielectric constant were calculated. All of the principal features and singularities of the dielectric functions for both compounds were found in the energy region between 2 eV and 20 eV. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In this work, we have investigated the electronic and optical properties of the technologically im- portant rare earth oxide compounds—X2O3 (X: Gd, Tb) using the density functional theory within the GGA. The band structure of X2O3 have been calculated along high symmetry directions in the first brillouin zone. The real and imaginary parts of dilectric functions and the other optical res- ponses such as energy-loss function, the effective number of valence electrons and the effective optical dielectric constants of the rare earth sesquioxides (Gd2O3 and Tb2O3) were calculated.

An investigation of the optical properties and band structures for the conventional and Fibonacci photonic crystals (PCs) based on SrTiO3 and Sb2Te3 is made in the present research. Here, we use one-dimensional SrTiO3- and Sb2Te3-based layers. We have theoretically calculated the photonic band structure and transmission spectra of SrTiO3- and Sb2Te3-based PC superlattices. The position of minima in the transmission spectrum correlates with the gaps obtained in the calculation. The intensity of the transmission depths is more intense in the case of higher refractive index contrast between the layers. This work is supported by the projects DPTHAMIT, DPT-FOTON, NATO-SET-193 and TUBITAK under Project Nos., 113E331, 109A015, 109E301. One of the authors (Ekmel Ozbay) also acknowledges partial support from the Turkish Academy of Sciences.

In present paper, we focus on the structural, mechanical, electronic, and optical properties for the A5B6C7(A = Sb, Bi; B = Te, Se; S; C = I, Br, Cl) compounds using the density functional methods in generalized gradient approximation. The lattice parameters, mechanical properties, electronic bands structures and the partial densities of states corresponding to the band structures, and optical properties are presented and analysed. Our structural estimation and some other results are in agreement with the available experimental and theoretical data.

In this study, we present an investigation of the optical properties and band structures for the photonic structures based on AIBIIICVI 2 with a Fibonacci sequence that can act as a multi-wavelength birefringent filter. The filtering wavelengths are analyzed by the indices concerning the quasi-periodicity of a Fibonacci sequence and the average lattice parameter. The transmittances of filtering wavelengths can be tuned by varying structure parameters such as the lengths of poled domains, filling factor, and dispersion relation. In our simulation, we employed the finite-difference time domain (FDTD) technique, which implies a solution from Maxwell equation.

In this study, we present the results of our ab initio calculation of the elastic constants, density of states, charge density, and Born effective charge tensors for ferroelectric (rhombohedral) and paraelectric phases (cubic) of the narrow band ferroelectrics (GeTe, SnTe) pseudopotentials. The related quantities such as bulk modulus and shear modulus using obtained elastic constants have also been estimated in the present work. The total and partial densities of states corresponding to the band structure of Sn(Ge)Te(S,Se) were calculated. We also calculated the Born effective charge tensor of an atom (for instance, Ge, Sn, Te, etc.), which is defined as the induced polarization of the solid along the main direction by a unit displacement in the perpendicular direction of the sublattice of an atom at the vanishing electric field. © Published under licence by IOP Publishing Ltd.

In the present work the acoustic band structure of a two-dimensional (2D) phononic crystal (PC) containing a semiconducting ferroelectric - AVBVICVII (A = Sb, Bi; B = S, Se, Te; C = I, Br, and Cl) was investigated theoretically and numerically by the plane-wave-expansion (PWE) method. Two-dimensional PC with square lattices composed of semiconducting ferroelectric cylindrical rods embedded in the organic/inorganic matrix is studied to find the existence of stop bands for the waves of certain energy. This phononic bandgap - forbidden frequency range - allows sound to be controlled in many useful ways in structures that can act as sonic filters, waveguides or resonant cavities. Phononic band diagram ω = ω(k) for a 2D PC was plotted versus the wavevector k along the Г-X-M-Г path in the square Brillouin zone (BZ). The band diagram shows four stop bands in the wide frequency range. The unusual properties of matrix and ferroelectric properties of AVBVICVII give us ability to control the wave propagation through the PC in over a wide frequency range. We study the 2D composites by solving the basic acoustic wave equation and use Bloch wave analysis to identify the band gaps.

In this study,we present an investigation of the optical properties and band structures for the conventional and Fibonacci photonic crystals (PCs) based on some A5B6C7 ferroelectrics (SbSBr and BiTeCl). Here, we use one dimensional SbSBr and BiTeCl based layers in air background. We have theoretically calculated the photonic band structure and transmission spectra of SbSBr and BiTeCl based PC superlattices. The position of minima in the transmission spectrum correlates with the gaps obtained in the calculation. The intensity of the transmission depths is more intense in the case of higher refractive index contrast between the layers. In our simulation, we employed the finite-difference time domain technique and the plane wave expansion method, which implies the solution of Maxwell equations with centered finite-difference expressions for the space and time derivatives. This work is supported by the projects DPT-HAMIT, DPT-FOTON, and NATO-SET-193 and TUBITAK under Project Nos., 113E331, 109A015, and 109E301. One of the authors (Ekmel Ozbay) also acknowledges partial support from the Turkish Academy of Sciences.

Quantitative structure-property relationship (QSPR) study on the acid dissociation constant, pKa of various 22 N-base ligands including pyridines, pyrimidines, purines, and quinolines has been carried out using Codessa Pro methodology and software. In addition, the formation constant, Kc of these ligands with Pt(II)(bpy)2 2+ (bpy = 2,2′-bipyridine) ion has also been modelled with the same methodology. Linear regression QSPR models of pKa and Kc were established with descriptors derived from AM1 calculations. Among the obtained QSPR models of pKa presented in the study, statistically the most significant one is a four parameters linear equation with the squared correlation coefficient, R2 values of ca. 0.95 and the squared cross-validated correlation coefficient, Rcv2 values of ca. 0.89, and external the squared correlation coefficient, Rext.2 values of ca. 0.97. Statistically the most significant QSPR model of Kc is also a four parameters linear equation with the squared correlation coefficient, R2 values of ca. 0.75 and the squared cross-validated correlation coefficient, Rcv2 values of ca. 0.55, and external the squared correlation coefficient, Rext.2 values of ca. 0.81. An analysis of descriptors that involved in the pKa models indicate that reactivity index and charge distribution related descriptors play major roles to model acid dissociation constant of ligands of N bases.

Several quantum-mechanics-based descriptors were derived for a diverse set of48 organic compounds using AM1, PM3, HF/6-31 G, and DFT-B3LYP/6-31 G (d) level ofthe theory. LC50 values of acute toxicity of the compounds were correlated to the fatheadminnow and predicted using calculated descriptors by employing ComprehensiveDescriptors for Structural and Statistical Analysis (CODESSA) program. The heuristicmethod, implemented in the CODESSA program for selecting the ‘best’ regression model,was applied to a pre-selection of the most-representative descriptors by sequentiallyeliminating descriptors that did not satisfy a certain level of statistical criterion. First model,statistically, the most significant one has been drawn up with the help of DFT calculationsin which the squared correlation coefficient R2 is 0.85, and the squared cross-validationcorrelation coefficient 2CV R is 0.79. Second model, which has been drawn up with the helpof HF calculations, has its statistical quality very close to the DFT-based one and in thismodel value of R2 is 0.84 and that of R2CV is 0.78. Third and fourth models have been drawnup with the help of AM1 and PM3 calculations, respectively. The values of R2 and R2CV in thethird case are correspondingly 0.79 and 0.66, whereas in the fourth case they are 0.78 and0.65 respectively. Results of this study clearly demonstrate that for the calculations of descriptors in modeling of acute toxicity of organic compounds to the fathead minnow, firstprincipal methods are much more useful than semi-empirical methods.Keywords: Comparative QSTR; fathead minnow; acute toxicity; DFT; HF

In this work, we present an investigation of the optical properties and band structure calculations for the photonic crystal structures (PCs) based on one-dimensional (1D) photonic crystal. Here we use 1D A5B6C7(A:Sb; B:S,Se; C:I) based layers in air background. We have theoretically calculated photonic band structure and optical properties of A5B6C7(A:Sb; B:S,Se; C:I) based PCs. In our simulation, we employed the finite-difference time domain (FDTD) technique and the plane wave expansion method (PWE) which implies the solution of Maxwell equations with centered finite-difference expressions for the space and time derivatives. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Analysis of the electronic states in two dimensional systems is of considerable interest for the exclusive use of 2D systems in microelectronic devices as well as for the close relation of this problem to investigations of the some quantum effects. In microelectronic devices, the coupling between the electron 2D subsystem and polarization (induced or spontaneous) is often effectuated by depositing a lattice on the surface of a film with the 2D gas. In this case, the electrons are subjected to an external (or internal) periodic potential, which makes it possible to investigate the electron spectrum in such system. In present paper, the spectrum of the electronic states in an infinitely deep two dimensional asymmetric potential well, where one wall is periodically rough, is investigated theoretically. It is shown that in non-Bragg type resonances arise in such well. The resonances occur in a wide range of energies, starting at values close to the bottom in each 2D sub-band. The resonance interaction splits the energy spectrum and results in the appearance of gaps, giving the electron spectrum a mini-band character. The properties of the electron gas vary substantially in accordance with the new characteristics of the spectrum.

20th International Conference on Ternary and Multinary Compounds (ICTMC) -- SEP 05-09, 2016 -- Halle, GERMANY, WOS: 000405267800024, In present work, our research is mainly focused on the electronic structures, optical, and magnetic properties of XMnSb (X = Ni, Cu, Pd), Co(2)YZ (Y = Ti; Z = Si, Ge, Sn), and Co(2)YZ (Y = Mn; Z = Al, Ga, Si) Heusler compounds by using ab initio calculations within the generalized gradient approximation. The calculations are performed by using the Vienna ab initio simulation package based on the density functional theory. The band structure of these Heusler alloys for majority spin and minority spin were calculated and the majority spin states cross the Fermi level and thus have the metallic character, while the minority spin states open the band gaps around the Fermi level and thus have the narrow-band semiconducting nature. We also find that these Heuslercompounds have the indirect band gaps in the minority spin channel. The real and imaginary parts of dielectric functions and hence the optical functions such as energy-loss function, the effective number of valance electrons and the effective optical dielectric constant for XMnSb and Co2YZ compounds were also calculated. In addition, we also show the variations of the total magnetic moment per f.u. and minority spin gap width of these compounds with optimized lattice constants: minority spin gap width decreases with increasing the lattice constants.

In present work, our research is mainly focused on the electronic structures, optical and magnetic properties of Cu2FeSnZ4 (Z = S, Se) compounds by using ab initio calculations within the generalized gradient approximation (GGA). The calculations are performed by using the Vienna ab-initio simulation package (VASP) based on the density functional theory. The band structure of the Cu2FeSnZ4 ( Z = S, Se) compounds for majority spin (spin-up) and minority spin (spin-down) were calculated. It is seen that for these compounds, the majority spin states cross the Fermi level and thus have the metallic character, while the minority spin states open the band gaps around the Fermi level and thus have the narrow-band semiconducting nature. For better understanding of the electronic states, the total and partial density of states were calculated, too. The real and imaginary parts of dielectric functions and hence the optical functions such as energy-loss function, the effective number of valance electrons and the effective optical dielectric constant for Cu2FeSnZ4 (Z = S, Se) compounds were also calculated. © Published under licence by IOP Publishing Ltd.

1 Department of Physics, Faculty of Sciences and Arts, Harran University, Osmanbey Campus, 63300, Sanliurfa, Turkey 2 Department of Chemistry, Faculty of Sciences and Arts, Harran University, Osmanbey Campus, 63300, Sanliurfa, Turkey *Author to whom correspondence should be addressed. E-mail: eeroglu@harran.edu.tr Abstract: This study presents Quantitative Structure Activity Relationships (QSAR) study on a pool of 18 bio-active sulfonamide compounds which includes five acetazolamide derivatives, eight sulfanilamide derivatives and five clinically used sulfonamides molecules as drugs namely acetazolamide, methazolamide, dichlorophenamide, ethoxolamide and dorzolamide. For all the compounds, initial geometry optimizations were carried out with a molecular mechanics (MM) method using the MM+ force fields. The lowest energy conformations of the compounds obtained by the MM method were further optimized by the Density Functional Theory (DFT) method by employing Becke’s three-parameter hybrid functional (B3LYP) and 6-31G (d) basis set. Molecular descriptors, dipole moment, electronegativity, total energy at 0 K, entropy at 298 K, HOMO and LUMO energies obtained from DFT calculations provide valuable information and have a significant role in the assessment of carbonic anhydrase (CA-II) inhibitory activity of the compounds. By using the multiple linear regression technique several QSAR models have been drown up with the help these calculated descriptors and carbonic anhydrase (CA-II) inhibitory data of the molecules. Among the obtained QSAR models presented in the study, statistically the most significant one is a five parameters linear equation with the squared correlation coefficient R

We report the results of electronic structure calculations for several types of MoO4-clusters in the Gd2(MoO4)3 structure in ferroelectric and paraelectric phase by using cluster ab initio restricted Hartree Fock method. The results give a variational approximation to the ground state electron densities of these clusters within the framework of ab initio restricted Hartree Fock (RHF) MO LCAO method.