Systematic investigation on the geometric dependence of the calculated nuclear magnetic shielding constants
Yan, Yijing（Hong Kong Univ Sci & Technol, Dept Chem）
- 化学化工－已发表论文 
We perform a systematic examination on the dependence of the calculated nuclear magnetic shielding constants on the chosen geometry for a selective set of density functional methods of B3LYP, PBE0, and OPBE. We find that the OPBE exchange-correlation functional performs remarkably well when either the optimized geometries or the experimental geometries are used. The popular B3LYP and PBE0 functionals have a clear tendency of deshielding, giving shieldings that are usually too low and shifts that are usually too high, at the experimental geometries. Combined with the Hartree-Fock geometries, however, much improved magnetic constants are obtained for B3LYP and PBE0, due to the compensation effect from the systematic Underestimation of bond lengths by the Hartree-Fock method. (c) 2008 Wiley Periodicals, Inc.