Baker Jon, Pulay Peter
Department of Chemistry, University of Arkansas, 115 Chemistry Building, Fayetteville, Arkansas 72701, USA.
J Comput Chem. 2003 Jul 30;24(10):1184-91. doi: 10.1002/jcc.10280.
We have investigated the performance of the OLYP and O3LYP density functionals for predicting atomic excitation energies and ionization potentials, and bond dissociation energies, geometries, and vibrational frequencies for selected first-row transition metal compounds, including hydrides (MH) and singly charged methylene and methyl cations. The OLYP and O3LYP functionals are similar to the well-known BLYP and B3LYP functionals, respectively, but use a new optimized exchange functional (OPTX) developed by Handy and Cohen (Mol Phys 2001, 99, 403) in place of the standard B88 exchange. A previous study by us on organic reactions (J Chem Phys 2002, 117, 1331) indicated that both OLYP and O3LYP gave results for heats of reaction and barrier heights that were overall superior to those using the popular B3LYP functional. For transition metals, however, although OLYP is overall superior to BLYP for molecular calculations, it is inferior to B3LYP. O3LYP provides results for molecules of about the same quality as B3LYP. For atomic excitation and 4s ionization energies, unless relativistic effects are included, OLYP and O3LYP are clearly worse than both BLYP and B3LYP. There is thus no real incentive to use either OLYP or O3LYP in place of B3LYP for calculations involving first-row transition metals.
我们研究了OLYP和O3LYP密度泛函在预测原子激发能、电离势以及选定的第一行过渡金属化合物（包括氢化物（MH）、单电荷亚甲基和甲基阳离子）的键解离能、几何结构和振动频率方面的性能。OLYP和O3LYP泛函分别类似于著名的BLYP和B3LYP泛函，但使用了由Handy和Cohen开发的新的优化交换泛函（OPTX）（《分子物理学》，2001年，99卷，403页）来取代标准的B88交换泛函。我们之前关于有机反应的一项研究（《化学物理杂志》，2002年，117卷，1331页）表明，OLYP和O3LYP给出的反应热和势垒高度的结果总体上优于使用流行的B3LYP泛函得到的结果。然而，对于过渡金属，虽然在分子计算中OLYP总体上优于BLYP，但它不如B3LYP。O3LYP给出的分子结果质量与B3LYP大致相同。对于原子激发能和4s电离能，除非考虑相对论效应，否则OLYP和O3LYP明显比BLYP和B3LYP都差。因此，在涉及第一行过渡金属的计算中，没有真正的动机用OLYP或O3LYP取代B3LYP。
