Electrostatic Interactions -- Electrophilic Susceptibility

Task: Generate and visualize the electrophilic susceptibility surface

for nitrocyclopentadiene  (). 

Time: 3 minutes

The electrophilic frontier density surface shows which regions of the molecule are most susceptible to electrophilic attack.

1. Open the file: File|Open "nitrocyclo-PM5".
2. Select Experiment|New. The experiment box opens
3. Select:
1. Property of: Chemical Sample
2. Property: electrophilic susceptibility
3. Using: PM5 geometry with PM5 wavefunction
4. Click Start.
4. The calculation window opens.  Information about the progress of the experiment scrolls in the window.  When the calculation is done, it will say "Tabulation complete".
5. Save the molecule: File|Save "nitrocyclo-PM5". 
6. Visualize the surface
   1. Select Analyze|Show Surfaces.   A Show Surfaces dialog box opens containing a list of Displayed surfaces.
   2. Locate the surface with the name nitrocyclo-PM5.csf.EFonD. The file names for other surfaces may be listed as well.  A check mark will appear when you click on the name nitrocyclo-PM5.csf.EFonD.
   3. Click OK.  Your molecule displays a surface colored to show areas of maximum electrophilic reactivity. 
7. Initially, the surface will be transparent; you can see the molecule "inside" the surface.  Clicking anywhere in the Workspace (no bonds or atoms) selects the surface.
8. To see what the different colors mean, select Analyze|Surface Legend.  A color legend appears. The smaller the number, the higher the reactivity toward electrophiles (H⁺, NO₂⁺, Br⁺).

In the next lesson, you will generate and display the Nucleophilic Susceptibility surface of nitrocyclopentadiene