Moment. Polarizability

The dipole moment i of N2H2 has not yet been experimentally determined. For trans- 2 2 li = 0 for reasons of symmetry. 

For C/S-N2H2, reliable quantum-chemical calculations gave dipole moments between 

0 (HF/3-21G(N )) [4], 3.06 (HF/triple- basis) [5], and 3.20 (HF/6-31G ) [6]. Results of previous ab initio calculations were given in [7 to 9]. Dipole moments calculated with semiempirical methods (CNDO, MNDO) were reported in [10 to 13]. 

Isotropic dipole polarizabilities for trans-H2y 2 and C/S-N2H2 were obtained by ab initio SCF calculations to be a= 18.18 and 18.53 ao. Hyperpolarizabilities were also calculated 

---

Many molecular properties can be related directly to the wave function or total electron density. Some examples are dipole moments, polarizability, the electrostatic potential, and charges on atoms. 

Their properties (dipole moment, polarizability, NMR coupling constants etc.). 

The most important calculated and experimental monomer data, such as equilibrium distances, dipole moments, polarizabilities, and the harmonic vibrational frequencies of the dihalogens XY, are reported in Tables 1-4. 

Experimental and theoretical results are presented for four nonlinear electrooptic and dielectric effects, as they pertain to flexible polymers. They are the Kerr effect, electric field induced light scattering, dielectric saturation and electric field induced second harmonic generation. We show the relationship between the dipole moment, polarizability, hyperpolarizability, the conformation of the polymer and these electrooptic and dielectric effects. We find that these effects are very sensitive to the details of polymer structure such as the rotational isomeric states, tacticity, and in the case of a copolymer, the comonomer composition. 

The nonlinear optical and dielectric properties of polymers find increasing use in devices, such as cladding and coatings for optical fibres, piezoelectric and optical fibre sensors, frequency doublers, and thin films for integrated optics applications. It is therefore important to understand the dielectric, optical and mechanical response of polymeric materials to optimize their usage. The parameters that are important to evaluate these properties of polymers are their dipole moment polarizability a, hyperpolarizabilities 0... 

We have shown in this paper the relationships between the fundamental electrical parameters, such as the dipole moment, polarizability and hyperpolarizability, and the conformations of flexible polymers which are manifested in a number of their electrooptic and dielectric properties. These include the Kerr effect, dielectric polarization and saturation, electric field induced light scattering and second harmonic generation. Our experimental and theoretical studies of the Kerr effect show that it is very useful for the characterization of polymer microstructure. Our theoretical studies of the NLDE, EFLS and EFSHG also show that these effects are potentially useful, but there are very few experimental results reported in the literature with which to test the calculations. More experimental studies are needed to further our understanding of the nonlinear electrooptic and dielectric properties of flexible polymers. 

Isotope Effects on Dipole Moments, Polarizability, NMR Shielding, and Molar Volume... 

Abstract Although the electronic structure and the electrical properties of molecules in first approximation are independent of isotope substitution, small differences do exist. These are usually due to the isotopic differences which occur on vibrational averaging. Vibrational amplitude effects are important when considering isotope effects on dipole moments, polarizability, NMR chemical shifts, molar volumes, and fine structure in electron spin resonance, all properties which must be averaged over vibrational motion. 

Table 12.1 Dipole moments, polarizabilities, and isotope effects for some diatomic and simple polyatomic molecules (ground vibrational state values)...

Induced Moments, Polarizability Isotope Effects 12.3.1 The Polarizability... 

Hydrogen bonding (hb) Dipole-dipole (dd) Dipole-induced dipole (di) Induced dipole-induced dipole (ii) Charge transfer (ct) qym, ME, orbital type dipole moment dipole moment, polarizability Polarizability ionization potential, electron affinity... 

Polar Molecule a molecule where the centers of positive and negative charge differ, creating a permanent dipole moment Polarizability ability of an electron cloud in a neutral atom to be distorted Polarized Light light in which the electromagnetic wave vibrates in only one plane Polyatomic Ion an ion consisting of more than one atom... 

Molecular descriptors vary gready in both their origins and their applications. They come from both experimental measurements and theoretical computations. Typical molecular descriptors from experimental measurements include logP, aqueous solubility, molar refractivity, dipole moment, polarizability, Hammett substituent constants, and other empirical physicochemical properties. Notice that the majority of experimental descriptors are for entire molecules and come directly from experimental measurements. A few of them, such as various substituent constants, are for molecular fragments attached to certain molecular templates and they are derived from experimental results. 

---