Gaussian 03 Online Manual
Last update: 13 February 2008


This properties keyword predicts NMR shielding tensors and magnetic susceptibilities using the Hartree-Fock method, all DFT methods and the MP2 method [232,234,528, 587].

NMR shielding tensors may be computed with the Continuous Set of Gauge Transformations (CSGT) method [231,233,235] and the Gauge-Independent Atomic Orbital (GIAO) method [226,227,228,229,230]. Magnetic susceptibilities may also be computed with both GIAOs [236,237] and CGST. Gaussian also supports the IGAIM method [231,233] (a slight variation on the CSGT method) and the Single Origin method, for both shielding tensor and magnetic susceptibilities.

Structures used for NMR calculations should have been optimized at a good level of theory. Note that CSGT calculations require large basis sets to achieve accurate results.

Spin-spin coupling constants may also be computed during an NMR job [238,239,240,241], via the SpinSpin option.

Compute spin-spin coupling constants in addition to the usual NMR properties. This calculation type has a computational cost of about twice that of computing vibrational frequencies. It is available only for Hartree-Fock and DFT methods.

Calculate spin-spin coupling constants only for selected atoms. The input is a free format list terminated with a blank line. Ranges of atoms are also allowed (e.g., 7-12).

Compute spin-spin coupling in two steps. In the first, the basis set specified by the user is modified to be appropriate for the Fermi Contact term, by uncontracting the basis and adding tight polarization functions for the core. In the second step, the other three terms in the spin-spin coupling are done with the standard basis. The final results reported at the end of the second job step include the Fermi Contact contribution from the first step. This significantly improves the accuracy of spin-spin coupling constants, especially when done with typical valence-oriented basis sets such as 6-31G** or Aug-CC-pVTZ.

Compute NMR properties using the CSGT method only.

Compute NMR properties using the GIAO method only. This is the default.

Use atomic centers as gauge origins.

Use a single gauge origin. This method is provided for comparison purposes but is not generally recommended.

Compute properties with all three of the SingleOrigin, IGAIM, and CSGT methods.

Display the eigenvectors of the shielding tensor for each atom

Compute only the Fermi contact spin-spin terms.

Read the Fermi contact spin-spin terms from the checkpoint file and then compute the other spin-spin coupling terms.

Compute the magnetic susceptibility as well as the shielding.

SCF, DFT and MP2 methods. In Gaussian 03, NMR may be combined with SCRF.

Here is an example of the default output from NMR:

Magnetic properties (GIAO method) 

Magnetic shielding (ppm): 
  1  C     Isotropic =    57.7345    Anisotropy =  194.4092 
   XX=     48.4143   YX=      .0000    ZX=      .0000 
   XY=       .0000   YY=   -62.5514    ZY=      .0000 
   XZ=       .0000   YZ=      .0000    ZZ=   187.3406 
  2  H     Isotropic =    23.9397    Anisotropy =    5.2745 
   XX=     27.3287   YX=      .0000    ZX=      .0000 
   XY=       .0000   YY=    24.0670    ZY=      .0000 
   XZ=       .0000   YZ=      .0000    ZZ=    20.4233 

For this molecular system, the values for all of the atoms of a given type are equal, so we have truncated the output after the first two atoms.

The additional output from spin-spin coupling computations appears as follows:

Total nuclear spin-spin coupling K (Hz): 
                1               2 
     1  0.000000D+00 
     2  0.147308D+02   0.000000D+00 
Total nuclear spin-spin coupling J (Hz): 
                1               2 
     1  0.000000D+00 
     2  0.432614D+03   0.000000D+00 

The various components of the coupling constants precede this section in the output file. It displays the matrix of isotropic spin-spin coupling between pairs of atoms in lower triangular form. The K matrix gives the values which are isotope-independant, and the J matrix gives the values taking the job's specific isotopes into account (whether explicitly specifed or the default isotopes).