GaussView is an affordable, full-featured graphical user interface for Gaussian 98. With GaussView you can construct molecular systems of interest quickly and efficiently using its molecule building facility. You can also set up and run Gaussian calculations right from the interface, and monitor their progress as they run. When a calculation has completed, you can use GaussView to examine a variety of results graphically via its advanced visualization facilities.
GaussView's Builder palette makes constructing molecules simple and fast. The molecule in the illustration is a platinum-olefin complex. This class of compounds are interesting in that the PtR2group has the ability to stabilize strained olefins upon formation of the complex. Here, we are in the process of completing the molecule by adding a benzene ring to the phosphorous atom on the right. We do so by selecting the desired ring from GaussView's Rings palette and then clicking on the existing hydrogen atom. We can then adjust the angle of the ring using other facilities on the Builder palette.
GaussView incorporates an excellent molecule builder which enables even very large molecules to be rapidly sketched in and then examined in three dimensions. It includes the following features:
GaussView's Gaussian Calculation Setup window allows you to specify any type of Gaussian calculation in a simple, straightforward manner. All of the features of Gaussian 98 are supported by the GaussView interface.
Gauss View can graphically display a variety of Gaussian calculation results, including the following:
Surfaces may be displayed in solid, translucent and wire-mesh modes. Surfaces can also be colored by a separate property. For example the illustrations below show the electrostatic potential-painted charge density surface for chloroform in both the solid (left) and translucent (right) display modes:
GaussView can produce graphical output containing any of the images that it generates. PostScript, JPEG and TIFF formats are supported. You can send such images to a printer for an immediate hard copy or export them to an external file for subsequent inclusion in documents or modification with graphical editing software.
Here we present a small study using Gaussian and GaussView illustrating how the two may be used in combination to investigate molecular systems.
The NMR shielding density for the methine proton of in-[3(4,10)]  metacyclophane is shown below (surface on the right), plotted on an isosurface of current density magnitude. (The molecule itself is pictured at the left.) Shielding density increases from red (deshielding) to blue (shielding). It was computed using Gaussian's NMR facility and visualized in GaussView.
The current density, which determines NMR shieldings by the Biot-Savart law, is induced by an external magnetic field parallel to the C3 axis and leads to an unusually large shielding of the methine proton. In accord with the classic ring current model, this result is primarily due to the strong diamagnetic phenyl ring currents and the location of the methine proton, which is calculated to be only 1.70 Angstroms above the phenyl ring. The calculated shielding anisotropy for the methine proton is 23.9 ppm while the calculated isotropic chemical shift is -4.4 ppm relative to TMS, in good agreement with the experimental value of -4.0 ppm.
We can compare these shielding densities to those for a phenyl proton in the same compound, shown in the illustration on the left. As before, the shielding density increases from red (deshielding) to blue (shielding). The current density is induced by an external magnetic filed parallel to the C3 axis and leads to a -3 ppm deshielding contribution to the phenyl proton from the bonded carbon and the two neighboring carbons.
The phenyl proton shielding is in sharp contrast to that for the methine proton (left the phenyl ring, along the C3 axis), where the shielding contribution from its own atom is the same as that for the phenyl proton. However, the bonded carbon shields the methine proton by over 5 ppm, and each phenyl ring carbon shields the methine proton by over 3 ppm, leading to a very large shielding of the methine proton. Once again, in accord with the classic ring current model, these results are primarily due to the strong diamagnetic phenyl ring currents and the location of the phenyl and methine protons.
Computed results and images for the NMR study were generated by James R. Cheeseman (Lorentzian, Inc.) and Roy Dennington and Todd Keith (Semichem, Inc.).