Comparison between CASPT2 and DFT in the study of Ni(C2H4)(2) complexes

被引:36
作者
Bernardi, F [1 ]
Bottoni, A [1 ]
Calcinari, M [1 ]
Rossi, I [1 ]
Robb, MA [1 ]
机构
[1] UNIV LONDON KINGS COLL, DEPT CHEM, LONDON WC2R 2LS, ENGLAND
关键词
D O I
10.1021/jp970998t
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
In this paper we report the results of a comparative theoretical study at the CASSCF/CASPT2 and DFT levels of the potential energy surface associated with bis(ethylene)-nickel complexes. The computations predict the existence on the potential surface of only one minimum of D-2d symmetry: the other critical points located on the surface (corresponding to structures of C-2v and D-2d symmetries) are saddle points of higher order. The results have pointed out that (i) the inclusion of dynamic correlation does not change the topology of the surface; (ii) the DFT approach provides for these systems results very similar to those obtained at the CASSCF/CASPT2 level; (iii) an effective core potential (ECP) basis (LANL2DZ) can provide a reliable description for these metal-olefin clusters. The second and third points are of particular interest since they indicate that it is possible to use a cheap approach (DFT with an ECP basis) to investigate larger nickel-olefin clusters with bulky ligands on the metal atom, as those involved in catalyzed cycloaddition reactions.
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收藏
页码:6310 / 6314
页数:5
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