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An explicit calculation of the quantum nonlocal (QNL) polarizability of a metallic nanoparticle is presented, where two quantum longitudinal plasma waves are excited. The QNL generalization of the classical Clausius–Mossotti factor of the system is derived, by means of the quantum hydrodynamic theory in conjunction with the Poisson equation and applying the appropriate additional quantum boundary conditions.

The static dipole polarizabilities of the 1 ¹S $\sim$ 5¹S, 2³S $\sim$ 6³S states of helium are presented. Our results are accurate up to at least eight digits. The majority of ${}^{\infty }$He (infinite mass helium) data are better than the data derived by Yan with Hylleraas coordinates,${}^{13}$ and close to the newest results achieved by another method.${}^{18}$ We demonstrate the results of ⁴He besides.

Ionization energies of a GaAs/Ga_1-xAl_xAs superlattice system with finite and infinite barriers are investigated with different dielectric screening functions within the effective mass approximation. Within the one-electron approximation the occurrence of Mott transition is seen when the binding energy of a donor vanishes. While the Thomas–Fermi screening function does not admit the Mott transition below a well-width around 60 Å,^1,2 the Hartree–Fock screening function with exchange and correlation effects included pushes the critical well-width to a value around 20 Å. The Lindhard screening function also gives the same results. The effects of Anderson localization and exchange and correlation in the Hubbard model are included in our model. It is found that the ionization energy (i) decreases as well-width increases, (ii) decreases when well-width increases and (iii) the critical concentration at which the metal-insulator transition occurs is lowered when well dimensions are reduced. All the calculations have been carried out with finite and infinite barriers and the results are compared with available data in the literature.

The dielectric properties of sodium silicate (Na₂SiO₃) (SS) have been investigated in a wide range of frequencies and temperatures. A strong dielectric dispersion is found to exist in low-frequency region. The frequency-dependent dielectric properties of SS follow the universal dynamic response proposed by Jonscher. The measured dielectric data strongly depends on dielectric dispersion and controls the basic relaxation property. However, the parameters that control the frequency-dependent dielectric properties such as coupling of ions or polarizability are found to have peak values at the frozen out condition or critical point.

A new optically nonlinear material, poly[N-(4-benzoylphenyl)-2-methylacrylamide], for conversion of wavelength 1064 nm to 532 nm has been synthesized. The material possesses strong electrical and optical nonlinearity required for second harmonic generation (SHG). The thin films of poly[N-(4-benzoylphenyl)-2-methylacrylamide] were prepared by the vacuum-deposition technique. The optical UV-visible, IR, NMR studies, mass spectrometry, surface topography and nonlinear optical properties of the thin films were studied. The vacuum-deposited thin films of the polymer were subjected to optimized high potential multi-point corona poling at temperatures just below the glass transition temperature (T_g) to create directional orientation of the side chain groups. The optical UV-visible absorption indicates a complete transparency in the visible and IR regions with an absorption peak at ~350 nm. The energy band gap of the polymer was estimated to be ~2.9 eV, from the optical absorption spectra of the thin films. The electrical current–voltage (IV) and optical nonlinear characteristic indicate the strong potential of these polymeric thin films for nonlinear optical (NLO) applications.

Dispersion properties of nanoarray waveguides composed of near-field-coupled arrays of metal-clad quantum dots (QDs) are calculated. The high loss due to operation of the metal shells close to resonance is mitigated by using optical gain in the QDs. The conditions for achieving loss compensated operation are given, with realistic material parameters and neglecting inhomogeneous broadening.

Density functional theory and Møller–Plesset perturbation theory methods have been used to study the ring clusters of (BN)_n=1–10 employing 6-311++G** basis set. The binding energies have been corrected for the basis set superposition error (BSSE). Static polarizability of these ring clusters has been investigated. A simple expression for the size dependence of polarizability has been invoked, so that the same relation can be useful for predicting the polarizability of larger clusters. The topological properties were analyzed employing the Bader's atoms in molecules theory. A good correlation between the structural parameters and the properties of electron density is found. Localization and delocalization indices were also used for the analysis of molecular electronic structure by an electron pair perspective. The contribution of stereo electronic interactions to the molecular properties as a function of ring size is analyzed based on the natural bond orbital (NBO) analysis.

Polarizability of small Si_n (n = 3 to 9) clusters has been calculated using density functional theory (DFT) with Vosko–Wilk–Nusair (VWN) correlation functional. The computed values of polarizability per atom tend to decrease with increasing cluster size. Frequency-dependent polarizability of Si₃, Si₄, Si₆, and Si₉ clusters demonstrates that the polarizability increases slowly with the increase in the energy for energy values less than 1.2 eV but exhibit the same size-dependent features as the static polarizability. The first resonance energy for Si₃, Si₄, Si₆, and Si₉ clusters occur at 1.25, 1.63, 2.5, and 1.98 eV, respectively. Moreover, the anisotropic polarizability is found to be the highest for Si₉ cluster.

In the last few years, plasmonics has attracted much attention and has been included in the principal domains of nanophotonics that can manage optical fields at the nanodimension level. Its exquisite characteristic is to increase the electromagnetic fields at the nanometer scale particularly in the solar cell. In the plasmonic discipline, noble metals used as nanoparticles in which the density of the electron gas which oscillates at surface plasmon frequency at that time also enhances absorption via scattering. So the usage of plasmonics in solar cells offers better possibility of improving the performance through absorption, because the optical spectrum loss is principal as a part of the overall loss for the solar photovoltaic cell. So we investigated the impact of the nanoparticle size for the enhancement of extinction in terms of absorption and scattering by using surface plasmon resonance, and additionally studied the finite-difference time domain (FDTD)-based proposed model and found various plasmonic fields components and characterized optical enhancement in the plasmonic thin film solar cell.

This paper presents dipole moments, static isotropic polarizabilities and polarizability anisotropies of 20 molecules calculated in the framework of a new natural orbital functional method. All calculations have been performed using a finite field approach. Comparison with other correlated methods (CCSD(T), B3LYP) shows a reasonable agreement in the prediction of electric response properties by this new functional.

A polarizability (α) based new scale of electronegativity (χ) is proposed. The basic algorithm is suggested by exploiting the fact that both polarizability and electronegativity are periodic properties and they are connected by an inverse relationship. Relying upon their express behavior along the periods of the periodic table, a general and straightforward relation between χ and α is suggested as χ = m(1/α)^1/3 + c, where m and c are constants. The constants m and c are evaluated by least square fitting by plotting χ vs. (1/α)^1/3 for each period separately. Thereafter, the suggested equation is used to evaluate the electronegativity, χ, of 54 elements from H to Xe in terms of least square fitted m and c, and a new set of atomic polarizabilities are computed by Ghosh and Biswas. The evaluated electronegativities exhibit periodicity of groups and periods and reproduce the silicon rule and the expected trend of variation of the electronegativities of d block transition metals. The evaluated electronegativities of the present semiempirical method are quite comparable with those computed by the rigorous mathematical method of Robles and Bartolotti. The efficacy of the new scale is also tested by computing the bond energy of a number of compounds. We have proposed a new formula relating the bond energy with the electronegativity difference. The proposed relation is given by D_AB - 〈D_AB〉= 3.8866Δχ + 0.0422, where 〈D_AA〉 = (D_AAD_BB)^1/2, Δχ represents the electronegativity difference, and D_AA, D_BB, and D_AB are the bond energies of homonuclear A–A, B–B, and hetero-nuclear A–B molecules. A comparative study of bond energies evaluated through the proposed relation, determined experimentally, and evaluated through other relations is also furnished. It is demonstrated that the proposed relation of computing the bond energy in terms of Δχ yields good bond energy values. Results demonstrate that the new polarizability based empirical scale of electronegativity is a fairly successful venture.

The geometrical and electronic structures of a series of dyads NMPC₆₀–AN_n (n = 1–5) were investigated at B3LYP/6-31G* level. Then, the excited states were calculated at TDB3LYP/3-21G* level to investigate the photophysical properties. The third-order polarizabilities of degenerate four-wave mixing (DFWM), electric-field-induced second-harmonic generation (EFISHG), and third-harmonic generation (THG) were calculated in combination with the sum-over-states (SOS) method. The obtained absorption spectra show a remarkable red shift. The average value of third-order polarizabilities 〈γ〉 away from the resonant region increases with n for NMPC₆₀–AN_n. The charge transfers from the oligoanilines to C₆₀ cage make the main contribution to the large third-order polarizabilities of this series of compounds. It is found that 〈γ〉 can be expressed as a function of the chain length of linked oligoaniline and 11.74 × 10^-34esu is the upper limit after n = 7 for NMPC₆₀–AN_n in the static state.

The next generation of Compton scattering experiments is underway at Mainz and other laboratories, where the goal is precision measurements of the scalar and vector polarizabilities of the nucleon using polarized photons and polarized targets. Results are presented for the first double polarized Compton scattering experiment utilizing a polarized proton target. Preliminary results are presented for the four spin polarizabilities of the proton.

The main experimental works, where dipole polarizabilities of charged pions have been determined, are considered. Possible reasons for the differences between the experimental data are discussed. In particular, it is shown that the account of the $\sigma$-meson gives a significant correction to the value of the polarizability obtained in the latest experiment of the COMPASS collaboration. We present also new fit results for the $\gamma \gamma \to {\pi }^{+}{\pi }^{-}$ reaction.

We have done geometry optimization of two conformers of Lantadene series C and D. The fundamental vibrational frequencies with intensity have been done by using B3LYP/6-311G (d, p) method. The complete vibrational assignments of wavenumbers are made on the basis of potential energy distribution (PED). The nonbonding interactions in Lantadenes C and D are calculated by using the same level theory at the bond critical point (BCP). The calculated topological parameters at BCP are utilized to determine the nature and strength of interactions. We have also computed HOMO–LUMO gap and plotted frontier orbital HOMO–LUMO surfaces, molecular electrostatic potential surfaces to explain the reactive nature of Lantadenes C and D. The electronic transition spectra UV–Vis spectra of Lantadenes C and D are calculated by using TDDFT theory. The values of hyperpolarizability show a probable use of these compounds in electro-optical applications. The natural bonding orbital theory is utilized to calculate transition of electron from donor to acceptor which is very useful to describe nonbonding as well as bonding interactions. The calculated value of Log $P$ and Log $S$ for Lantadene C Lantadene D established its pharmaceutical behaviors. The biological activity of Lantadenes C and D is also calculated by using PASS online server for $\mathrm{\text{Pa}}>70\%$. The docking of Lantadene C Lantadene D is also performed by using Auto dock with predicted drug by Swiss dock online server.

Pyruvate anion is important in a broad array of physicochemical processes ranging from glucose homeostasis to atmospheric reactions. However, the electronic polarizability of the moiety has not been investigated extensively. We present theoretical results from electronic structure calculations on the static and dynamic polarizability of microhydrated pyruvate anions. These investigations were carried out with the CH₃COCOO${}^{-}\cdot$n H₂O clusters ($n=1$–9) to mimic microhydration conditions. These density functional theory calculations were carried out at the B3LYP/aug-cc-PVTZ level to uncover the optimal geometry of the anion water cluster. Sadlej basis set functions with the B3LYP functional were used to calculate the static and dynamic polarizabilities. Multiple simulated annealing simulations were carried out to discover additional low-lying minima. It is observed that the electronic polarizability varies linearly with the size of the hydrated cluster. Expressions that describe the relationship between the dynamic polarizability and the field frequency are provided for each cluster.

A scheme we have formulated recently for partitioning the total dipole moments and polarizabilities of finite systems into site-specific contributions is used to analyze the structure-/shape- and size-specific aspects of the dipole moments and polarizabilities of small sodium clusters. The procedure is based on dividing the system volume into cells associated with its atoms. The site-specific, or atomic, dipole moments and polarizabilities are computed from the charge densities within the individualcells (“atomic volumes”) and the changes in these densities in response to an external electric field. The atomic dipole moments and polarizabilities are further partitioned into local (or “dipole”) and “charge-transfer” components. It is shown that the polarizabilities associated with the individual Na atoms vary considerably with the structure/shape of the cluster and the location of the atom within a given structure. Surface atoms, especially those at edges, have larger polarizabilities than interior atoms. The contribution of the charge-transfer components to the total polarizability increases with the cluster size.

The stability of an organic compound depends on its nature and the environment in which it is placed. It depends on the presence or absence of reagents (acid, base, oxidizing agent, reducing agent, light, etc.) and catalysts. The stability may not be the same in the solid, liquid or gaseous state. In a homogenous solution, the stability might be affected by the polarity of the solvent and its concentration. For instance a polar solvent favors ionization. In a non-polar solvent ionization is difficult. In the gas phase ionization never occurs. In the gas phase and in solution stability depends on pressure and the presence of impurities. We are interested here in the thermal stability of pure compounds in the gas phase or in non-polar solvents under one atmosphere…

The nucleon spin structure has been an active, exciting and intriguing subject of interest for the last three decades. Recent experimental data on nucleon spin structure at low to intermediate momentum transfers provide new information in the confinement regime and the transition region from the confinement regime to the asymptotic freedom regime. New insight is gained by exploring moments of spin structure functions and their corresponding sum rules (i.e. the generalized Gerasimov-Drell-Hearn, Burkhardt-Cottingham and Bjorken). The Burkhardt-Cottingham sum rule is verified to good accuracy. The spin structure moments data are compared with Chiral Perturbation Theory calculations at low momentum transfers. It is found that chiral perturbation calculations agree reasonably well with the first moment of the spin structure function g₁ at momentum transfer of 0.05 to 0.1 GeV² but fail to reproduce the neutron data in the case of the generalized polarizability δ_LT (the δ_LT puzzle). New data have been taken on the neutron (³He), the proton and the deuteron at very low Q² down to 0.02 GeV². They will provide benchmark tests of Chiral dynamics in the kinematic region where the Chiral Perturbation theory is expected to work.