A DFT study of a model compound of vitamin D

A theoretical study of a model compound of vitamin D was carried out by mea ns of DFT calculations. In particular, the B3LYP functional with the 6-31G* basis set was used to perform the investigations. Five energy minima of th e model compound were optimised in this work (one of them in a folded arran gement). The results of this study agree with our previous HF calculations on the same model compound (E. Martinez-Nunez, S. A. Vazquez, and R. A. Mos quera, J. Comp. Chem., 18, 1647 (1997)) and contrast markedly with semiempi rical and force field calculations. However, a discrepancy between the HF a nd the present DFT geometries and relative energies appears for the folded conformation, demonstrating that for this conformation, correlation effects are important. For geometries, our results are found to be in good agreeme nt with X-ray crystallographic data. (C) 1999 Elsevier Science B.V. All rig hts reserved.