TY - JOUR

T1 - Shielding

T2 - Overview of Theoretical Methods

AU - Karadakov, Peter B.

AU - Webb, Graham A.

N1 - Publisher Copyright:
© 2008 by John Wiley and Sons, Ltd.

PY - 2011

Y1 - 2011

N2 - This chapter presents a concise overview of the quantum-chemical approaches that can be used in order to obtain theoretical estimates of NMR shielding tensors and associated quantities, such as isotropic shieldings, chemical shifts, and shielding anisotropies. The chapter starts with a brief outline of the main equations that define the shielding tensor in terms of the electronic Hamiltonian for a molecule in a uniform magnetic field and the corresponding wavefunction, and of the gauge-origin problem which needs to be addressed in most finite-basis calculations. This is followed by a discussion of the most important factors that influence the computed NMR shielding tensors, and have to be accounted for in accurate calculations, including electron correlation effects, relativistic effects, ro-vibrational corrections, and solvent effects. Special attention is given to the calculation of NMR shielding tensors for large molecules, as well as to the availability of quantum-chemical codes capable of performing shielding calculations at different levels of theory.

AB - This chapter presents a concise overview of the quantum-chemical approaches that can be used in order to obtain theoretical estimates of NMR shielding tensors and associated quantities, such as isotropic shieldings, chemical shifts, and shielding anisotropies. The chapter starts with a brief outline of the main equations that define the shielding tensor in terms of the electronic Hamiltonian for a molecule in a uniform magnetic field and the corresponding wavefunction, and of the gauge-origin problem which needs to be addressed in most finite-basis calculations. This is followed by a discussion of the most important factors that influence the computed NMR shielding tensors, and have to be accounted for in accurate calculations, including electron correlation effects, relativistic effects, ro-vibrational corrections, and solvent effects. Special attention is given to the calculation of NMR shielding tensors for large molecules, as well as to the availability of quantum-chemical codes capable of performing shielding calculations at different levels of theory.

UR - http://www.scopus.com/inward/record.url?scp=85122781139&partnerID=8YFLogxK

U2 - 10.1002/9780470034590.emrstm0498.pub2

DO - 10.1002/9780470034590.emrstm0498.pub2

M3 - Article

AN - SCOPUS:85122781139

SN - 2055-6101

VL - 8

SP - 4457

EP - 4468

JO - eMagRes

JF - eMagRes

ER -