Correlated and gauge invariant calculations of nuclear magnetic shielding constants using the continuous transformation of the origin of the current density approach

A recently developed methodology for calculating, analyzing, and visualizing nuclear magnetic shielding densities is used for studying spatial contributions including ring-current contributions to 1H nuclear magnetic resonance (NMR) chemical shifts of aromatic and anti-aromatic free-base porphyrinoids. Our approach allows a visual inspection of the spatial origin of the positive (shielding) and negative (deshielding) contributions to the nuclear magnetic shielding constants. Diatropic and paratropic current-density fluxes yield both shielding and deshielding contributions implying that not merely the tropicity of the current density determines whether the contribution has a shielding or deshielding character. Instead the shielding or deshielding contribution is determined by the direction of the current-density flux with respect to the studied nucleus.

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Invariance of multipole polarisabilities of nuclear magnetic shielding within the approach of continuous transformation of the origin of the current density

Theoretical Chemistry Accounts ◽

10.1007/s00214-007-0359-6 ◽

2007 ◽

Vol 118 (5-6) ◽

pp. 863-868 ◽

Cited By ~ 3

Author(s):

P. Lazzeretti ◽

M. B. Ferraro ◽

G. I. Pagola ◽

M. C. Caputo

Keyword(s):

Current Density ◽

Magnetic Shielding ◽

Continuous Transformation ◽

Nuclear Magnetic

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Gauge‐invariant calculation of nuclear magnetic shielding constants at the coupled–cluster singles and doubles level

The Journal of Chemical Physics ◽

10.1063/1.469397 ◽

1995 ◽

Vol 102 (1) ◽

pp. 251-253 ◽

Cited By ~ 156

Author(s):

Jürgen Gauss ◽

John F. Stanton

Keyword(s):

Coupled Cluster ◽

Magnetic Shielding ◽

Gauge Invariant ◽

Shielding Constants ◽

Nuclear Magnetic

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MP2 calculation of nuclear magnetic shielding constants involving gauge-invariant bases

Canadian Journal of Chemistry ◽

10.1139/v88-287 ◽

1988 ◽

Vol 66 (7) ◽

pp. 1781-1785 ◽

Cited By ~ 22

Author(s):

Edouard C. Vauthier ◽

Michel Comeau ◽

Simone Odiot ◽

Sandor Fliszar

Keyword(s):

Nuclear Magnetic Resonance ◽

Spin Rotation ◽

Basis Set ◽

Magnetic Shielding ◽

Resonance Spectroscopy ◽

Correlation Effects ◽

Gauge Invariant ◽

Atomic Orbitals ◽

Shielding Constants ◽

Nuclear Magnetic

Dia- and paramagnetic shielding constants of HF, NH3, N2, H2O, and CO were calculated in the 4-31G, 4-31G*, and 6-31G** bases, using gauge-invariant atomic orbitals. Correlation effects were evaluated by 2nd-order perturbation theory: while the diamagnetic contributions are virtually unaffected by correlation, the paramagnetic parts (σρ) are modified by ~10 ppm in the 6-31G** basis. With or without correlation, calculated σρ values differ significantly from results obtained from measured spin-rotation constants. However, improvements in the basis set descriptions and inclusion of correlation yield chemical shift values for 15N and 17O converging toward their experimental counterparts obtained from conventional nuclear magnetic resonance spectroscopy.

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