Welcome to the CAChe Molecular Modeling Tutorials

Department of Chemistry

University of Pittsburgh at Johnstown

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Molecular Orbitals -- I

Task: Optimize the geometry of ammonia using MOPAC (PM5)

Time: 2 minutes

The first step in generating MO surfaces for a molecule requires that we optimize the geometry. If necessary, review the tutorial on Geometry Optimization before getting started.

  1. Open the file with ammonia molecule you built earlier. File|Open "ammonia"
  2. If you optimized the structure in the previous module, skip to the next lesson.
  3. If you have not already done so, optimize it using MOPAC
    1. Select Experiment|New  
    2. Property of: chemical sample
    3. Property: optimized geometry
    4. Using: PM5 geometry
    5. Click Start.
  4. Save the file. File|Save As "ammonia-PM5"

Now that we have the electronic information from the MOPAC calculations, we can generate the molecular orbital surfaces.