Hyperpolarizabilities of extended molecular mechanical systems

2016 ◽  
Vol 18 (12) ◽  
pp. 8710-8722 ◽  
Author(s):  
Ignat Harczuk ◽  
Olav Vahtras ◽  
Hans Ågren
Keyword(s):  
Dipole Moments ◽  
Mechanical Systems ◽  
Second Order ◽  
Dipole Model ◽  
Point Dipole ◽  
Induced Dipole

The equations for decomposition of the molecular hyperpolarizabilty into atomic sites is derived alongside with equations to calculate the cluster hyperpolarizability as resulting from the second order induced dipole moments in the point-dipole model.

scholarly journals Space Charge Property of Polyethylene/Silica Nanocomposites at Different Elongations

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Can Wang ◽  
Youyuan Wang ◽  
Peng Fan ◽  
Ruijin Liao
Keyword(s):  
Particle Size ◽  
Space Charge ◽  
Dipole Model ◽  
Particle Sizes ◽  
Test Results ◽  
Silica Nanocomposites ◽  
Induced Dipole ◽  
Interface Characteristics ◽  
Space Charge Distribution ◽  
Charge Property

This paper prepares polyethylene/silica nanocomposites with concentrations of 3 wt% and 5 wt% by using silicon dioxide (SiO2) nanopowder (nanosilica) with particle sizes of 15 and 50 nm. Samples whose elongations are 3%, 6%, and 10% are prepared. Pulsed electroacoustic technique is applied to evaluate the space charge distribution in samples. Test results show that homocharge near electrodes is generated in the polyethylene/silica nanocomposites. Nanocomposites with a nanoparticle concentration of 3 wt% and particle size of 15 nm suppress the accumulation of space charge effectively. The amount of space charge in the samples increases with the increase in elongation. At an elongation of 10%, packet-like space charge is generated in polyethylene/silica nanocomposites with the concentration of 5 wt% and particle sizes of 15 and 50 nm. The packet-like space charge in nanocomposites whose particle size is 50 nm is more obvious than that in nanocomposites whose particle size is 15 nm. The experiment results are explained by applying interface characteristics, dipole model, and induced dipole model.

Intensity of the Pressure-Induced Fundamental Infrared Band of Gaseous Chlorine

1973 ◽  
Vol 51 (6) ◽  
pp. 696-697 ◽  
Author(s):  
P. T. T. Wong ◽  
E. Whalley
Keyword(s):  
Dipole Moments ◽  
Good Evidence ◽  
Transition Moment ◽  
Infrared Band ◽  
Fundamental Band ◽  
Induced Dipole ◽  
Integrated Intensity ◽  
Type Interaction

The integrated intensity of the pressure-induced fundamental band of gaseous chlorine measured by Winkel, Hunt, and Clouter is about 5 times that calculated assuming that the transition moment arises from the oscillation of quadrupole-induced dipole moments. This provides good evidence that valence-type interaction between gaseous chlorine molecules occurs.

THE INVESTIGATION OF ELECTRONIC PROPERTIES AND MICROSCOPIC SECOND-ORDER NONLINEAR OPTICAL BEHAVIOR OF 1-SALICYLIDENE-3-THIO-SEMICARBAZONE

2007 ◽  
Vol 16 (01) ◽  
pp. 91-99 ◽  
Author(s):  
ASLI KARAKAS ◽  
HUSEYIN UNVER ◽  
AYHAN ELMALI
Keyword(s):  
Molecular Orbital ◽  
Electronic Transition ◽  
Nonlinear Optical ◽  
Dipole Moments ◽  
Empirical Method ◽  
Second Order ◽  
Nlo Properties ◽  
Calculation Results ◽  
Moller Plesset ◽  
Semi Empirical

To investigate the microscopic second-order nonlinear optical (NLO) behavior of the 1-salicylidene-3-thio-semicarbazone Schiff base compound, the electric dipole moments (μ), linear static polarizabilities (α) and first static hyperpolarizabilites (β) have been calculated using finite field second-order Møller-Plesset perturbation (FF MP2) theory. The ab-initio results on (hyper)polarizabilities show that the investigated molecule might have microscopic NLO properties with non-zero values. To understand the NLO behavior in the context of molecular orbital structure, we have also examined the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) and the HOMO-LUMO gap in the same theoretical framework as the (hyper)polarizability calculations. In addition to the NLO properties, the electronic transition spectra have been computed using a semi-empirical method (ZINDO). ZINDO calculation results show that the electronic transition wavelengths have been estimated to be shorter than 400 nm.

scholarly journals GFN2-xTB - an Accurate and Broadly Parametrized Self-Consistent Tight-Binding Quantum Chemical Method with Multipole Electrostatics and Density-Dependent Dispersion Contributions

2018 ◽  
Author(s):  
Christoph Bannwarth ◽  
Sebastian Ehlert ◽  
Stefan Grimme
Keyword(s):  
Dispersion Model ◽  
Dipole Moments ◽  
Tight Binding ◽  
Density Fluctuations ◽  
Second Order ◽  
Conformational Space ◽  
Semiempirical Methods ◽  
Nuclear Forces ◽  
Binding Model ◽  
Molecular Systems

An extended semiempirical tight-binding model is presented, which is primarily designed for the fast calculation of structures and non-covalent interactions energies for molecular systems with roughly 1000 atoms. The essential novelty in this so-called GFN2-xTB method is the inclusion of anisotropic second order density fluctuation effects via short-range damped interactions of cumulative atomic multipole moments. Without noticeable increase in the computational demands, this results in a less empirical and overall more physically sound method, which does not require any classical halogen or hydrogen bonding corrections and which relies solely on global and element-specific parameters (available up to radon, <i>Z=86</i>). Moreover, the atomic partial charge dependent D4 London dispersion model is incorporated self-consistently, which can be naturally obtained in a tight-binding picture from second order density fluctuations. Fully analytical and numerically precise gradients (nuclear forces) are implemented. The accuracy of the method is benchmarked for a wide variety of systems and compared with other semiempirical methods. Along with excellent performance for the “target” properties, we also find lower errors for “off-target” properties such as barrier heights and molecular dipole moments. High computational efficiency along with the improved physics compared to it precursor GFN-xTB makes this method well-suited to explore the conformational space of molecular systems. Significant improvements are futhermore observed for various benchmark sets, which are prototypical for biomolecular systems in aqueous solution.<br><br>

Exact results for light scattering by dense systems of isotropic particles: How good is the DID model

1981 ◽  
Vol 59 (10) ◽  
pp. 1560-1562 ◽  
Author(s):  
T. Keyes ◽  
P. A. Madden
Keyword(s):  
Light Scattering ◽  
Lattice Gas ◽  
Dipole Model ◽  
Exact Results ◽  
Double Scattering ◽  
Dominant Mechanism ◽  
Simple Liquids ◽  
Dense Lattice ◽  
Exact Theory ◽  
Induced Dipole

An exact, computationally convenient, expression for light scattering by a dense lattice gas is presented. It is shown how the exact theory can be used as a benchmark to test the assumption always made so far, that "pair" or "double" scattering is the dominant mechanism for depolarization by simple liquids. The tenability of the dipole – induced dipole model may be determined by the outcome of the indicated test.

scholarly journals Recovering of the Membrane Profile of an Electrostatic Circular MEMS by a Three-Stage Lobatto Procedure: A Convergence Analysis in the Absence of Ghost Solutions

Mathematics ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 487 ◽  
Author(s):  
Mario Versaci ◽  
Giovanni Angiulli ◽  
Alessandra Jannelli
Keyword(s):  
Convergence Analysis ◽  
Electrostatic Field ◽  
Mean Curvature ◽  
Mechanical Systems ◽  
Numerical Approach ◽  
Second Order ◽  
Circular Membrane ◽  
Differential Model ◽  
The Mean

In this paper, a stable numerical approach for recovering the membrane profile of a 2D Micro-Electric-Mechanical-Systems (MEMS) is presented. Starting from a well-known 2D nonlinear second-order differential model for electrostatic circular membrane MEMS, where the amplitude of the electrostatic field is considered proportional to the mean curvature of the membrane, a collocation procedure, based on the three-stage Lobatto formula, is derived. The convergence is studied, thus obtaining the parameters operative ranges determining the areas of applicability of the device under analysis.

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