Welcome to the CAChe Molecular Modeling Tutorials

Department of Chemistry

University of Pittsburgh at Johnstown

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Visualizing Steric Interactions -- Getting Started

Task: Build and optimize 1,2-dichloroethane.

Time: 2 minutes

  1. Begin with the ethane molecule you built in an earlier tutorial module.

    1. File|Open "ethane"

    2. Save with the new name: File|Save As "12Cl2ethane"

  2. Convert ethane to 1,2-dichloroethane .
    1. Use the atom tool, , select chlorine and make sure the hybridization is sp3 .
    2. Click in the center of one carbon atom and drag away from the atom. A chlorine will appear when you release the mouse key. Repeat on the other carbon atom.
    3. Choose the select tool, , and click anywhere in the Workspace to select the whole molecule.
    4. To fix the geometry, select Beautify|Comprehensive from the menu bar. 
  3. Optimize the molecule 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 "12Cl2ethane-PM5"

We "built" our target molecule and generated the electronic information from the MOPAC calculations. We'll proceed to compare Ball & Stick structure with the Space Filling model.