Welcome to the CAChe Molecular Modeling Tutorials

Department of Chemistry

University of Pittsburgh at Johnstown

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Molecular Orbitals -- III

Task: Visualize the MO surfaces of ammonia

Time: 3 minutes

Since we computed all of the MO surfaces, we can visualize them all at one once (gets confusing if there are lots of MOs) or one at a time.

  1. Open the file if necessary (File|Open ammonia)
  2. Select Analyze|Show Surfaces.  A Show Surfaces dialog box opens containing a list of Displayed surfaces.
  3. Locate the surface ending in .MO4.  When you click on the surface label, a check mark appears to the left. Click OK.  Your molecule displays the highest occupied molecular orbital (HOMO).
  4. Use the rotate button,, to visualize all sides of the orbital surface.
  5. To view other MO surfaces, select Analyze|Show Surfaces, click on the HOMO surface; the check mark next to ammonia-PM5.csf.MO4 disappears. Select another (.MO5 will be the lowest unoccupied molecular orbital or LUMO).

Note: As a general rule, the check mark next to the surface label in the Show Surfaces window disappears when you deselect a surface and it appears by the name of the new surface that you select.  If you select more than one surface label, they all appear in the Workspace window.

These Molecular Orbital surfaces are pretty "cool", but it might seem like you are using a "black box" to generate the pictures.  Actually, the MO surfaces can give us some very useful information about the molecules as you'll see in the modules that follow.   In the next tutorial module you will learn to compute and display spectral properties of a molecule or ion.