On The Use Of F And G Sum Rules As Error Indicators Of Experimental Vibrational Intensity Data: The Chxd3-xbr Molecules

[No abstract available]70115338533

G-intensity Sum Rule Applications: Xy3 Molecules

Using the pyramidal XY3 (X=N, P; Y=H, F) molecules as examples, the G-intensity sum rule of Crawford, expressed in terms of effective charges, is shown to be an effective test of the numerical results of vibrational analyses. Errors in previously reported effective charge values for NF 3 and PF3 are corrected. Values for the as yet unreported polar tensors of these molecules are presented. Comparisons of these results with those previously reported for other molecules are made. © 1978 American Institute of Physics.68125448545

Experimental Determination Of Relative Signs Of Dipole Moment Derivatives: Hcn And Dcn

An alternative numerical analysis for the experimental determination of the relative signs of the dipole moment derivatives with respect to the normal coordinates is presented. Use is made of the polar tensor and effective charge equations and the G-intensity sum rule of Crawford. The relative signs are determined by sufficiently accurate individual infrared fundamental intensities of one molecule and only the sum of these intensities for an isotopically related molecule. The intensity data of HCN and DCN are used to illustrate the procedure. The as yet unreported values of the atomic polar tensors and effective charges of these molecules are also reported. © 1978 American Institute of Physics.68384785

F And G Intensity Sum Rule Applications: The Chxd4-x Molecules

Numerical analyses based on the F and G intensity sum rules show that recently published experimental values for the fundamental vibrational intensities of CH4, CH3D, CH2D2, CHD3, and CD4 are internally consistent within experimental errors. Effective charge values for the carbon and hydrogen atoms obtained using the intensity sums for all these isotopically related molecules are almost in exact agreement with reported values obtained from the polar tensors of CH4 and CD4. The G sum rule allows a determination of the signs of the dipole moment derivatives using the fundamental intensity sum for CH4 (or CD4) and the polar tensor values for CD4 (or CH4). © 1978 American Institute of Physics.6994147414

Simulation of an industrial wastewater treatment plant using artificial neural networks and principal components analysis

This work presents a way to predict the biochemical oxygen demand (BOD) of the output stream of the biological wastewater treatment plant at RIPASA S/A Celulose e Papel, one of the major pulp and paper plants in Brazil. The best prediction performance is achieved when the data are preprocessed using principal components analysis (PCA) before they are fed to a backpropagated neural network. The influence of input variables is analyzed and satisfactory prediction results are obtained for an optimized situation.365370Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Atomic Charge Transfer-counter Polarization Effects Determine Infrared Ch Intensities Of Hydrocarbons: A Quantum Theory Of Atoms In Molecules Model

Atomic charge transfer-counter polarization effects determine most of the infrared fundamental CH intensities of simple hydrocarbons, methane, ethylene, ethane, propyne, cyclopropane and allene. The quantum theory of atoms in molecules/charge-charge flux-dipole flux model predicted the values of 30 CH intensities ranging from 0 to 123 km mol-1 with a root mean square (rms) error of only 4.2 km mol-1 without including a specific equilibrium atomic charge term. Sums of the contributions from terms involving charge flux and/or dipole flux averaged 20.3 km mol-1, about ten times larger than the average charge contribution of 2.0 km mol-1. The only notable exceptions are the CH stretching and bending intensities of acetylene and two of the propyne vibrations for hydrogens bound to sp hybridized carbon atoms. Calculations were carried out at four quantum levels, MP2/6-311++G(3d,3p), MP2/cc-pVTZ, QCISD/6-311++G(3d,3p) and QCISD/cc-pVTZ. The results calculated at the QCISD level are the most accurate among the four with root mean square errors of 4.7 and 5.0 km mol-1 for the 6-311++G(3d,3p) and cc-pVTZ basis sets. These values are close to the estimated aggregate experimental error of the hydrocarbon intensities, 4.0 km mol-1. The atomic charge transfer-counter polarization effect is much larger than the charge effect for the results of all four quantum levels. Charge transfer-counter polarization effects are expected to also be important in vibrations of more polar molecules for which equilibrium charge contributions can be large. This journal is16422322423232King, W.T., Mast, G.B., Blanchette, P.P., (1972) J. Chem. Phys., 56, p. 4440Gribov, L.A., (1964) Intensity Theory for Infrared Spectra of Polyatomic Molecules, , Consultants Bureau, N. YDecius, J.C., (1975) J. Mol. Spectrosc., 57, p. 348Straten, A.J., Smit, W.M.A., (1976) J. Mol. Spectrosc., 62, p. 297Gussoni, M., Jona, P., Zerbi, G., (1983) J. Chem. 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Cndo Calculation Of Dipole Moment Derivatives And Infrared Intensities Of Formaldehyde

The complete neglect of differential overlap (CNDO) approximate wavefunctions for formaldehyde have been applied to the calculation of the derivatives of the dipole moment with respect to the symmetry coordinates (∂p/∂Sj). Agreement between the calculated derivatives and the experimental values given by Hisatsune and Eggers for the A1 symmetry species is exceptionally good, permitting an interpretation of the experimental results in terms of electronic distributions in the molecule. The agreement for the B1 and B2 symmetry species is also very good except for the asymmetric in-plane CH bend. However, the theory successfully predicts that charge reorientation for this motion is quite different from that which occurs in the out-of-plane CH bend, so that these motions are represented by CH bond moments of opposite polarity. An analysis is given of the results in terms of derivatives with respect to internal coordinates (∂p/∂rk). Comparison of ∂p/∂rCS values from a series of X2CO molecules (and also with ∂p/∂rcs for X2CS molecules) reveals an interesting trend. An analysis of the various contributions to the calculated ∂p/∂rk values is presented, with an explanation of the calculated results for the out-of-plane bending coordinate ∂p/∂γ.5862585259

The Theoretical Calculation Of Polar Tensors And Dipole Moment Derivatives: Bf3 And Bcl3

The experimental and CNDO polar tensors for BF3 and BCl 3 are reported. To satisfy charge and symmetry restrictions the importance of the calculation of limiting values for theoretical polar tensor elements is demonstrated. A convenient method to transform polar tensor elements to ∂p/∂Qi values is presented. The atomic effective charges, mean dipole moment derivatives, and anisotropics of BF3 and BCl3 are reported and discussed. Copyright © 1976 American Institute of Physics.6473053305

Infrared Gas Phase Intensity Measurements. Polar Tensors And Effective Charges Of Cis-dichloroethylene-d0 And D2

The gas phase fundamental intensities of cis-dichloroethylene and its dideuterated modification have been measured. Isotopic invariance, the G sum rule and the results of molecular orbital calculations have been used to select preferred experimental values for the dipole moment derivatives and polar tensor elements of these molecules. The F sum rule has been used to determine individual intensity values of the v4, v12 overlapped band system of the dihydrogen molecule. Values of the polar tensor elements for cis dichloroethylene are compared with those previously determined for cis-difluoroethylene. The hydrogen effective charge values in these molecules are essentially identical (0.17 and 0.18e). The polar tensor of cis-dichloroethylene is used to predict the vibrational intensities of trans-dichloroethylene. © 1983 American Institute of Physics.791192

Infrared Gas Phase Intensity Measurements, Polar Tensors, And Effective Charges Of Vinylidene Fluoride And Its Deuterated Modifications

All gas phase fundamental vibrational intensities for vinylidene fluoride and its deuterated modifications have been measured. Isotopic invariance, G sum rule, and quantum chemical information have been used in selecting preferred experimental values for the dipole moment derivatives and polar tensor elements of these molecules. The values of these intensity parameters are compared with those found for other molecules. The experimental values are interpreted in terms of electronic charge distortions occurring in these molecules for the various vibrations. © 1982 American Institute of Physics.7731099110