Transition metal NMR chemical shifts from optimized effective potentials

J Chem Phys. 2007 Feb 21;126(7):074101. doi: 10.1063/1.2436876.

Abstract

Metal shielding constants and chemical shifts are determined for nine transition metal complexes using an uncoupled formalism with orbitals and eigenvalues determined using the Yang-Wu implementation [W. Yang and Q. Wu, Phys. Rev. Lett. 89, 143002 (2002)] of the optimized effective potential approach in density functional theory. Preliminary calculations using generalized gradient approximation functionals quantify the influence of the variables in the optimized effective potential implementation. In particular, a flexible potential expansion is necessary for a precise calculation of these quantities. Hybrid functionals are then considered. Expanding the potential in the primary orbital basis yields chemical shifts that are a notable improvement over conventional hybrid values, and which are a marginal improvement over those obtained using a high-quality generalized gradient approximation. Similar shifts are obtained using a more flexible potential expansion, although care is required to avoid unphysical structure in the exchange-correlation potential.