Ab initio, model calculations

With the aid of 13C NMR, 6Li NMR and XH HOESY (heteronuclear Overhauser effect spectroscopy) NMR of a-lithiomethoxyallene (106) and l-lithio-l-ethoxy-3-J-butylallene (107) as well as by ab initio model calculations on monomeric and dimeric a-lithiohy-droxyallene, Schleyer and coworkers64 proved that 106 and 107 are dimeric in THF (106 forms a tetramer in diethyl ether) with a nonclassical 1,3-bridged structure. The 13C NMR spectrum of allenyllithium in THF is also in agreement with the allenic-type structure the chemical shift of C2 (196.4 ppm) resembles that of neutral allene (212.6 ppm), rather than C2 of propyne (82.4 ppm). 

Raman spectroscopy, ab initio model calculations and conformational equilibria in ionic liquids... 

Ab initio and semiempirical molecular orbital (MO) model calculations have become an efficient way to predict chemical structures and vibrational (i.e., Raman scattering and IR emission) spectra. We and others have used such approaches to better understand certain features of fhe specfra, as explained in the following. The basic principles underlying ab initio model calculations have been described in many textbooks and papers (see for example Refs. 44,47,48). Applications in relation to ILs and similar systems have also been reported, as discussed later. 

The CP-MET equations represent a non-linear coupled system of equations which for a long time has resisted direct solution. The first ab initio model calculation using CP-MET was published by Paldus et in 1972, a more realistic application by Taylor et al. in 1976. Although considerable progress has been made recently in this field,"it is probably fair to say that the CP-MET is too involved to call it a minor modification of the CI(SD). 

Berg, R.W., Raman spectroscopy and ab-initio model calculations on ionic liquids, Monatsh. Chem. 138 (11), 1045-1075 (2007). 

The acid-base and base-base interactions of the N-tabelled side-chain amino groups of dry solid poly-L-lysine and the consequences for the secondary structure have been studied using high-resolution solid-state and CP MAS NMR spectroscopy and ab initio model calculations. " ... 

Radziszewski, J.G., J. Abilgaard, and E.W. Thulstrup. 1997. The vibrational spectrum of acenaphthylene linear dichroism and ab initio model calculations. Spectrochim. Acta 53A 2095-2107. 

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