DFT force fields, vibrational spectra and potential functions for hinderedinternal rotation of CF3CH2CH2Cl and CCl3CH2CH2Cl

The fully optimized geometries and vibrational frequencies of trans- and ga uche-conformers of CF3CH2CH2Cl and CCl3CH2CH2Cl were obtained at the B3LYP and BLYP levels of hybrid functional theory DFT with the different basis se ts. Corresponding ab initio calculations were also performed at the HF and MP2 levels of theory. DFT calculations using Becke's exchange and Lee-Yang- Parr correlation functional give a correct picture of the relative stabilit y of different conformers and present rather good agreement of calculated a nd experimental frequencies. On this basis, the regularized quantum mechani cal force field (RQMFF) for both trans- and gauche-conformers of CF3CH2CH2C l and CCl3CH2CH2Cl were obtained. (C) 1999 Elsevier Science B.V. All rights reserved.