Characteristic frequency approach

M. E. Elyashberg, Infrared spectra interpretation by the characteristic frequency approach, in The Encyclopedia of Computational Chemistry,... 

The problem of the interpretation of vibrational spectra is to calculate all possible combinations of substructures that may be present in a molecule consistent with the characteristic frequencies of a given infrared spectrum. Elyashberg and his team showed with an example that the infrared spectrum-structure correlation, as simply expressed by the characteristic frequency approach, does not allow one to establish the structure unambiguously due to a lack of information in characteristic frequencies [32]. They pointed out that the use of ANNs appears to be particularly promising. 

It appears that the first layer is relatively unpolarizable and the dielectric constant in the order of three but, with an average of only two layers, the dielectric constant was in the order of thirty for a frequency of 100 Hz. The characteristic frequency is 1 kHz. Evidence indicates clusters of water being heterogeneously distributed. As the thickness increases beyond three layers, the characteristic frequency approaches that of ice, suggesting a development of hydrogen bonding between water molecules. 

Algorithms Infrared Data Correlations with Chemical Structure Infrared Spectra Interpretation by the Characteristic Frequency Approach Machine Learning Techniques in Chemistry Molecular Models Visualization Neural Networks in Chemistry NMR Data Correlation with Chemical Structure Partial Least Squares Projections to Latent Structures (PLS) in Chemistry Shape Analysis Spectroscopic Databases Spectroscopy Computational Methods Structure Determination by Computer-based Spectrum Interpretation Zeolites Applications of Computational Methods. 

Carbocation Force Fields Carbocation Stabilities Comparison of Theory and Experiment Carbohydrate Force Fields Carbohydrates Conformational Analysis 1 Conformational Analysis 2 Conformational Analysis 3 Force Fields A Brief Introduction Force Fields A General Discussion Infrared Spectra Interpretation by the Characteristic Frequency Approach Natural Bond Orbital Methods Solvation Carbohydrates Transition States in Organic Chemistry Ab Initio. 

INFRARED SPECTRA INTERPRETATION BY THE CHARACTERISTIC FREQUENCY APPROACH 1307... 

Infrared Spectra Interpretation by the Characteristic Frequency Approach... 

This example is quite typical and shows clearly that the IR spectrum-structure correlations, as expressed by the characteristic frequency approach, on their own do not allow one to establish the structure unambiguously, owing to the lack of information carried by characteristic frequencies. However, this approach can successfully be used for the selection of probable fragments and for forming fragment sets capable of interpreting the IR spectrum. 

Infrared Data Correlations with Chemical Structure Infrared Spectra Interpretation by the Characteristic Frequency Approach Neural Networks in Chemistry NMR Chemical Shift Computation Ab Initio NMR Chemical Shift... 

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