The choice of the exchange-correlation functional for the determination of the jahnteller parameters by the density functional theory

The JahnTeller (JT) parameters for small, aromatic, organic radicals, CnHn (n = 47), bis(cyclopentadienyl)cobalt(II) (cobaltocene), a sodium cluster (Na3), a silver cluster (Ag3), the hexaflurocuprate(II) ion ([CuF6]4), and tris(acetylacetonato)manganese(III) ([Mn(acac)3]) have been evaluated by the means of the multideterminantal density functional theory using the most common approximations, to clarify which type of exchange-correlation functional should be used in analysis of the JT effect. The results are compared with available experimental and theoretical data. The choice of the functional strongly depends on the chemical system at hand, but to obtain fast and qualitatively reliable results, the local density approximation may be taken as satisfactory, regardless of the diversity of the systems prone to a JT distortion. (c) 2012 Wiley Periodicals, Inc.