Dynamic Electric Properties Research Articles

Relating the crystal structure and third-order nonlinear susceptibility of a new Neolignan derivative

Theoretical results for electronic properties of a synthesized nitro chalcone with a neolignan moiety (NOPP) whose crystal structure was elucidated by using Single Crystal X-ray Diffraction (SCXRD) are presented. The NOPP crystal structure suggests that its potential for nonlinear applications is related to the chalcone moiety planarity and that the lamellar NOPP crystal packing along with dimer formation maximize the electronic properties. The in-crystal absorption spectrum and static and dynamic electric properties were determined by applying a supermolecule approach in combination with an iterative electrostatic scheme, in which the surrounding molecules are represented by point charges. It is found that the environment polarization effect is mild for absorption spectrum and linear polarizability, but it is marked for second hyperpolarizability of NOPP molecule. Estimates of macroscopic quantities from the results of an explicit unit cell of crystal, including environment polarization effect and partially the exchange and dispersion effects, are presented. The results illustrate the role played by these interactions on the third-order nonlinear susceptibility of the NOPP crystal, and a theoretical (λ=532nm) prediction of 2.81×10−20 (m/V)2 for χ(3)(−ω;ω,ω,ω) suggests that the NOPP crystal is a very promising NLO material.

Multiphysics CFD Simulation for Design and Analysis of Thermoelectric Power Generation

The multiphysics simulation methodology presented in this paper permits extension of computational fluid dynamics (CFD) simulations to account for electric power generation and its effect on the energy transport, the Seebeck voltage, the electrical currents in thermoelectric systems. The energy transport through Fourier, Peltier, Thomson and Joule mechanisms as a function of temperature and electrical current, and the electrical connection between thermoelectric modules, is modeled using subgrid CFD models which make the approach computational efficient and generic. This also provides a solution to the scale separation problem that arise in CFD analysis of thermoelectric heat exchangers and allows the thermoelectric models to be fully coupled with the energy transport in the CFD analysis. Model validation includes measurement of the relevant fluid dynamic properties (pressure and temperature distribution) and electric properties (current and voltage) for a turbulent flow inside a thermoelectric heat exchanger designed for automotive applications. Predictions of pressure and temperature drop in the system are accurate and the error in predicted current and voltage is less than 1.5% at all exhaust gas flow rates and temperatures studied which is considered very good. Simulation results confirm high computational efficiency and stable simulations with low increase in computational time compared to standard CFD heat-transfer simulations. Analysis of the results also reveals that even at the lowest heat transfer rate studied it is required to use a full two way coupling in the energy transport to accurately predict the electric power generation.

Mechanical and electric properties of ferroelectric Ba1-xCaxTiO3 ceramic

A comparative study on the dynamic mechanical and electric properties was firstly performed on Ba1-xCaxTiO3 (x = 0.1 ∼ 0.25) ceramics. A diphasic ceramic composed of ferroelectric tetragonal Ba0.8Ca0.2TiO3 and normal dielectric orthorhombic Ba0.07Ca0.93TiO3 solid solutions was obtained near the solubility limit (x = 0.23). The ferroelectric to paraelectric phase transition was clearly characterized by dynamic mechanical analysis (DMA) and dielectric spectrum, but the orthorhombic-to-tetragonal phase transformation for Ba0.9Ca0.1TiO3 was only detected by DMA. Relatively lower internal friction and higher remnant polarization near the solubility limit (x = 0.21–0.25) were found. In addition, the influence of poling and annealing on the mechanical properties of BCT ceramic was investigated.

Efficient polarized basis sets for evaluation of static and dynamic molecular electric properties

New medium size Gaussian-type basis set R-ORP for evaluation of static and dynamic electric properties in molecular systems is presented. It is obtained in a close resemblance to the original ORP basis set, from the source basis set through addition of two first-order polarization functions whose exponent values are optimized with respect to the finite field restricted open-shell Hartree–Fock (ROHF) atomic polarizabilities. As the source set the VTZ basis set of Ahlrichs and coworkers, augmented with additional diffuse functions and contracted to the form [6s/3s] for hydrogen and [11s7p/4s3p] for carbon through fluorine, is chosen. The resulting basis set is of the form [6s2p/3s2p] for hydrogen and [11s7p2d/4s3p2d] for other atoms. Presented basis set is next tested in the CCSD static and dynamic molecular polarizability and hyperpolarizability calculations for a set of ten and four test molecules, respectively, for which very accurate reference data exist. Additionally, the recently developed ORP basis set is employed in the calculations to examine the limits of its applicability. Results are compared to the literature data obtained in both, large and diffuse, as well as reduced-size basis sets. In the case of polarizability calculations, the aug-pc-1 and R-ORP are the optimal choices among the investigated smaller basis sets, with the overall performance of the aug-pc-1 set being better. Among the larger sets, the ORP performs better in the case of average polarizability, while the RMSE values for polarizability anisotropy are practically identical for d-aug-cc-pVDZ and ORP sets. Finally, the R-ORP and ORP basis sets compete other small bases in the evaluation of the first hyperpolarizability in investigated systems. © 2016 Wiley Periodicals, Inc.

Polarized basis sets for accurate calculations of static and dynamic electric properties of molecules

We report on the development and testing of large polarized basis sets (LPolX, where X is the element symbol) for accurate calculations of linear and nonlinear electric properties of molecules. The method used to generate LPolX sets is based on our studies of the analytic dependence of Gaussian functions on external time-independent and time-dependent electric fields. At variance with the earlier investigations of small, highly compact (ZPolX) basis sets for moderately accurate calculations of electric properties of large molecules, the present goal is to obtain basis sets that are nearly saturated with respect to the selected class of electric properties and can be used for accurate studies of interaction-induced properties. This saturation makes the LPolX sets also useful in calculations of optical properties for chiral molecules. In this article, the LPolX sets are generated for X = H, C, N, O, and F, and examined in calculations of linear and nonlinear electric properties of four standard test systems: HF, N(2), CO, and HCN. The study of the performance of LPolX basis sets has been carried out at different levels of approximation ranging from the SCF HF method to highly correlated CCSD(T) approach. The results obtained in this study compare favorably with accurate reference data and show a high level of saturation of LPolX basis sets with respect to the polarization effect due to external electric fields.

Hysteresis of Soft Materials Inside Formulations: Delayed Diffusion Equations, Fields Coupling, and Nonlinear Properties

The aim of this paper is to propose and argue specific electromagnetic formulations including dynamic electric and magnetic properties of soft materials, working with transient signals and time harmonics within the quasi-static approximation. Special attention will be paid to origin, nature, and relevance of these so-called dynamic properties, which will act on both the diffusion process and coupling between regions. Nonlinear transient experimental identifications of a homogenized dynamic magnetic property are also carried out and discussed. It can provide useful experimental data of soft magnetic materials for simulation and conception purposes.

Vibrational effects on the dynamic electric properties of hydrogen peroxide

In this work we present a method based on the perturbation theoretic approach of Bishop and co-workers [J. Chem. Phys. 95, 2646 (1991); 97, 5255 (1992); 108, 10013 (1998)] to calculate the effect of torsional motion on the polarizability and hyperpolarizabilities of hydrogen peroxide. The frequency dependence has been evaluated using the time-dependent Hartree-Fock method. The results obtained show that the zero-point vibrational averaging contributions are small compared to the corresponding electronic contributions. In the static limit the pure vibrational contributions are very large, specially for beta and gamma. These contributions are significant for the hyperpolarizabilities even in the visible region, except for the second harmonic generation and third harmonic generation processes.

Derivation of dynamic electric and magnetic response properties based on the quasienergy derivative method

We present a response theory based on the quasienergy derivative (QED) method in which not only the electric dipole interaction but also the magnetic dipole and diamagnetic interactions are considered as interactions between a (spin- and orbit-nondegenerate) molecular system and a time-dependent electromagnetic field. The QED method-based systematic derivation of dynamic electric and magnetic response properties in an exact theory and two approximate models (time-dependent Hartree-Fock (TDHF) and (orbital-nonrelaxed) coupled-cluster (CC) theories) is shown. Among dynamic electric and magnetic response properties, we present the explicit derivation of electric dipole-magnetic dipole polarizability ($G_{A,E}(-ω_1;ω_1)$), magnetizability ($χ_{EF}(-ω_1;ω_1)$), and hypermagnetizability ($η_{AB,EF}(-ω_σ;ω_1,ω_2,ω_3)$).

Derivation of dynamic electric and magnetic response properties based on the quasienergy derivative method

We present a response theory based on the quasienergy derivative (QED) method in which not only the electric dipole interaction but also the magnetic dipole and diamagnetic interactions are conside...

A comparative study of the vibrational corrections for the dynamic electric properties of the LiF molecule using numerical and perturbation methods

In this work we report results of CPHF calculations, including vibrational corrections, for the dynamic polarizability and first hyperpolarizability of the LiF molecule. Vibrational corrections were computed through the Numerov–Cooley and perturbation-theoretic methods. Comparison between the results obtained using both methods shows that first-order perturbation-theoretic provides a good approximation for the zpva contribution. The double-harmonic-oscillator approximation is reliable for the pv contributions of α zz , β xxz and β zxx , while [ μα] 0 + [ μ 3] I is a good approximation for β zzz . CCSD(T) results obtained for the pv contribution show that the electron correlation effects are small for the polarizability but significant for the first hyperpolarizability.

Vibrational contributions to the dynamic electric properties of the NaF molecule

In this work, we report calculations of the vibrational corrections to the dynamic polarizability and first hyperpolarizability of the NaF molecule performed through the CPHF method. We have considered frequencies varying from 0 to 0.12 hartree. Results obtained show that the zpva contributions are small in comparison with the corresponding electronic contributions. It is shown that both contributions can be well described by quartic polynomial fits. The pv contributions are important on the vibrational range of frequencies but negligible on the visible region, except for β xxz (− ω ; ω ,0) and β zzz (− ω ; ω , 0). A detailed study of the pv contributions over the range of vibrational frequencies, including an electron correlation treatment at the CCSD(T) level, is presented.