NMR Spectra

The Results=>NMR menu item displays the spectrum from an NMR calculation. An example spectrum is shown below.

r_nmr.tif
NMR Spectrum Display

This is the default NMR display format. It displays all computed peaks. Clicking on a peak with the cursor displays the shielding value and degeneracy in the lower left corner of the window (e.g., peak 2-C above).

The fields at the bottom of the NMR Spectra window allow you to view the same data as relative values with respect to TMS or other standards. To use this feature, first select the desired element in the leftmost popup menu, and then select one of the available standard calculation results from the Reference field. The peaks will then reflect relative values with respect to the selected reference:

r_shifts.tif
Displaying NMR Chemical Shifts

Clicking on a peak in this display mode shows the numeric chemical shift with respect to the specified standard in the lower left corner of the window. The corresponding shielding value is displayed in the Shielding field.

r_shifts.tif
Modifying NMR Plot Properties

The properties of the NMR plot can be modified by using the Plots=>Properties menu path. GaussView offers the ability to modify the peak half-width at half height using the corresponding box on the dialog. The degeneracy tolerance can also be modified in this dialog. An example of modifying the peak half-width at half height is shown below.

r_nmr_1.tif
r_nmr_2.tif

The NMR Spectra graph can also be customized using the Mixture Editor. More information on the Mixture Editor can be found here.

Adding New Reference Results

The data subdirectory of the main GaussView directory contains the nmr.data, which holds refernce data for NMR displays. This is an ordinary text file, and it can be modified with any text-editing software. However, you must take care to user maintain the existing format. It is prudent to make a backup copy of the file before adding to or modifying it.

The fields shown below, left to right, are: element symbol, predicted shielding value, and menu item label (typically the reference compound and model chemistry). We have added the line in red for the APFD/6-311+G(2d,p) model chemistry.

# Sym Shielding Description
C 199.9853 "TMS HF/6-31G(d) GIAO"
C 182.4656 "TMS B3LYP/6-311+G(2d,p) GIAO"
C 187.435 "TMS APFD/6-311+(2d,p) GIAO"
C 199.1 "CH4 HF/6-31G(d) GIAO"
H 32.5976 "TMS HF/6-31G(d) GIAO"
H 31.8821 "TMS B3LYP/6-311+G(2d,p) GIAO"
Si 449.7802 "TMS HF/6-31G(d) GIAO"
Si 327.3890 "TMS B3LYP/6-311+G(2d,p) GIAO"
N 260.8 "NH3 HF/6-31G(d) GIAO"
N 258.4 "NH3 B3LYP/6-311+G(2d,p) GIAO"
O 323.1 "H2O HF/6-31G(d) GIAO"
O 320.0 "H2O B3LYP/6-311+G(2d,p) GIAO"
B 106.7 "B2H6 HF/6-31G(d) GIAO"
B 83.6 "B2H6 B3LYP/6-311+G(2d,p) GIAO"

Quotation marks are required if the description includes spaces. A pound sign (#) in the first column indicates a comment.