Statistical analysis dipole moments

Using a 70-drug set, Ghafourian et al., conducted a statistical analysis of computed chemical descriptors to predict human VD [36]. The descriptors found to provide a predictive model included logP, logDi, and Pmm (a measure of dipole moment), in a linear regression ... 

Interactions between nonbonded atoms and groups in this chain are found to be either identical with or similar to interactions arising in PE, POM, and POE. Statistical weights obtained in the analysis of the dimensions and dipole moments of these chains are thus applicable to the present investigation of the polyltetramethylene oxide) chain, The calculated dipole moments are in good agreement with preliminary published results obtained on the undiluted, amorphous polymer. 

Because of convention, the symbols for the chemical potential, used in Equation 6.44 and Equation 6.45, and the dipole moment are the same. Further evaluation of Equation 6.48 proceeds through introduction of the LCAO-MO expansion (Equation 6.18) and, dependent on the level of theory, consideration of relevant approximations such as the NDDO formalism (Equation 6.31) in the case of semiempirical MNDO-type methods. Because the calculation of the dipole moment is usually considered a somewhat demanding test of the quality of the wavefunctions employed in the quantum chemical model, this property is included in the comparative statistical analysis of various methods to calculate molecular descriptors as presented in Section V. 

The previous discussion pointed out some well-known limitations of the different theoretical approaches currently used to analyse polarization effects and estimate the dipole moment in the liquid phase. We will focus the present analysis of polarization effects in HB liquids on results obtained by using the sequential statistical mechanics/quantum mechanics approach. 

For a QSAR analysis a training set of compounds with known descriptor properties (e. g. pKa-values, surface areas, dipole moments etc.), including the property of interest, is required. The Hansch Analysis1461 is a statistical method to analyze and correlate these data in order to determine the magnitude of the target property (Eq. 2.15). 

In a collection of statistically distributed, mobile dipolar species, the total field-parallel contribution to the polarization is the statistical average over the cos 5 projections on the field vector. For the sake of transparentness we shall confine the further analysis to uniaxial anisotropic particles Bj, i.e., to uniaxial dipole moments m. In this case Eqs. (3.12) and (3.16) read, respectively,... 

Dipole moment is the molecular dipole moment in Debyes. Our original analysis was based on dipole moments calculated from Gasteiger-Hiickel point charges and the experimentally observed molecular geometries. Later tests showed that dipole moments from geometry optimised AMI wave functions give virtually the same statistical results. 

In Chapter 15, we conclude our exposition of molecular electronic structure theory by applying the standard models of quantum chemistry to the calculation of a number of molecular properties equilibrium stmctures, dipole moments, electronic energies, atomization energies, reaction enthalpies, and conformational energies. The performance of each model is examined, comparing with the other models and with experimental measurements. The large number of molecular systems considered enables us to carry out a statistical analysis of the different methods, making... 

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