Dipole moments parameters

Liquid T (K) A. Fitted Parameters Parameters Relevant to a Rigid Dipole Moment Parameters Relevant to a Nonrigid Dipole Moment ... 

Curran et al. [ 16] conclude their analysis of the 1A NF spectrum by comparing the magnitudes of the magnetic hyperfine, quadrupole and dipole moment parameters with predictions from self-consistent field calculations due to O Hare and Wahl [19]. The agreement is satisfactory, and one supposes that contemporary calculations would be in even better agreement with experiment. One of the main purposes of the measurements and spectral analysis described in this section is to provide accurate benchmarks for theoretical calculations, and also physical insight into the nature of the molecular bonding. 

VSTR = O Connell characteristic volume parameter, cm /g-mol ZRA = Rackett equation parameter RD = mean radius of gyration, A DM = dipole moment, D R = UNIQUAC r Q = UNIQUAC q QP = UNIQUAC q ... 

DIPOLE MOMENT OF COMPONENT I fDEBYES ASSOCIATION OR SOLVATION PARAMETER FOR T E (I.JI PAIR... 

The SPC/E model approximates many-body effects m liquid water and corresponds to a molecular dipole moment of 2.35 Debye (D) compared to the actual dipole moment of 1.85 D for an isolated water molecule. The model reproduces the diflfiision coefficient and themiodynamics properties at ambient temperatures to within a few per cent, and the critical parameters (see below) are predicted to within 15%. The same model potential has been extended to include the interactions between ions and water by fitting the parameters to the hydration energies of small ion-water clusters. The parameters for the ion-water and water-water interactions in the SPC/E model are given in table A2.3.2. 

Surface electron charge density can be described in tenus of the work fiinction and the surface dipole moment can be calculated from it ( equatiou (Bl.26.30) and equation (B1.26.31)). Likewise, changes in the chemical or physical state of the surface, such as adsorption or geometric reconstruction, can be observed through a work-fimction modification. For studies related to cathodes, the work fiinction may be the most important surface parameter to be detenuined [52]. 

In stead, the electrostatic con tribn tion conies from definin g a set of bond dipole moments associated woth polar bonds. These bond moments are defined in the m m psir.LxL(dbf) file along with the bond stretching parameters and are given in units of Debyes. The cen ter of th e dipole Is defined to be th e m Idpoint of the bond an d two dipoles p. and pj. separated by Rjj. as shown beltnv ... 

If the MMh- option to use bond dipoles for nonbonded electrostatic calculations is set, then MM-t ignores atomic charges but uses dipole moments supplied in its parameter set (in the mmpstr. files). 

The conformational characteristics of PVF are the subject of several studies (53,65). The rotational isomeric state (RIS) model has been used to calculate mean square end-to-end distance, dipole moments, and conformational entropies. C-nmr chemical shifts are in agreement with these predictions (66). The stiffness parameter (5) has been calculated (67) using the relationship between chain stiffness and cross-sectional area (68). In comparison to polyethylene, PVF has greater chain stiffness which decreases melting entropy, ie, (AS ) = 8.58 J/(molK) [2.05 cal/(molK)] versus... 

Compound CAS Registry Number Boiling point, °C Density at 20°C, g/cm Dipole moment, 10-"° Cm Index of refraction, < PR nmr Parameters chemical t shift, ppm ... 

Viscosity. A corresponding states method that requires critical pressure, temperature, and dipole moment has been developed for low pressure gas viscosity (221). This method, which includes a group contribution parameter, is also appHcable to gas mixtures. Whereas a group contribution method is not available for dipole moment, the influence this parameter has can be neglected for many species. 

The microwave spectrum of isothiazole shows that the molecule is planar, and enables rotational constants and NQR hyperfine coupling constants to be determined (67MI41700>. The total dipole moment was estimated to be 2.4 0.2D, which agrees with dielectric measurements. Asymmetry parameters and NQR coupling constants show small differences between the solid and gaseous states (79ZN(A)220>, and the principal dipole moment axis approximately bisects the S—N and C(4)—C(5) bonds. 

There were also several calculations of geometrical parameters, dipole moment and energy of oxaziridine 71MI50800). Since the parent compound of oxaziridines is unknown, comparison of calculated and experimental values is still lacking. 

For both polar and nonpolar nonhydrocaihon gaseous mixtui es at low pressui es, the most accurate viscosity prediction method is the method of Brokaw. The method is quite accurate but requires the dipole moment and the Stockmayer energy parameter (e/A ) for polar components as well as pure component viscosities, molecular weights, the normal boding point, and the hq-uid molar volume at the normal boding point. The Technical Data Manual should be consulted for the fidl method. 

All properties (energy, dipole moment, atomic charges) and geometry parameters (distance, angle, dihedral angle) can be animated or stepped through. 

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