1. Double click on the PC Spartan Pro icon, , and then click "File" in the upper left corner of the PC Spartan Pro window.
   
   



2. Select "New" from the pop-up menu.
   
   



3. Click the "Expert" tab in the "model kit" located on the right .
   
   



4. Select "B" from the periodic table and the sp² jack in the "model kit."
   
   



5. Place the cursor in the center of the window and click the left button on the mouse.
   
   



6. Hold the left button on the mouse down and move the cursor horizontally to rotate the model around the z-axis.
   
   



7. Hold the "Shift" button on the keyboard down and press the right button on the mouse. Move the cursor vertically to increase (up) or decrease (down) the size of the model. To center the model in the window, place the cursor on the model, hold the right button on the mouse down, and move the model to the center of the window.
   
   



8. For other functions associated with the mouse and for help with the software click "Help" in the top, right corner of the window and then click the "On-Line Help" button. Click the pull-down menu in the "On-Line Help" window to observe topics for which help is available.
   
   



9. Select "H" from the periodic table and click the button in the "Model Kit." Place the cursor at the end of the a stick representing a sp₂ hybrid orbital on the boron atom and click the left button on the mouse to attach a hydrogen atom to the boron atom.
   
   



10. Attach hydrogen atoms to the remaining sp₂ hybrid orbitals (sticks) on the boron atom in the same manner.
    
    



11. Finally, click the button to initiate a molecular mechanics program. Bond angles and lengths are varied until a minimum in the molecular-mechanics potential energy is obtained. The molecular geometry found at the minimum is used as the starting geometry for the optimization calculations.
    
    

Determination of the Molecular Geometry Associated with a Minimum on the Potential Energy Surface

1. Click "Setup" in the tool bar.
   
   



2. Select "Calculations" in the pop-up menu. When the "Setup Calculations" window appears, click on the first pull-down menu in the "Calculate:" row and select "Equilibrium Geometry."
   
   



3. Select "Semi-Empirical" from the second pull-down menu as the method or level of calculation.
   
   



4. Pick "AM1" as the type of semi-empirical method from the third pull-down menu in the row labeled "Calculate:."
   
   



5. Since the molecular geometry (atomic coordinates) obtained from the molecular mechanics minimization will be used as the starting geometry for the optimization calculation, select "Initial" from the pull-down menu in the row labeled "Start from:." BH₃ is a neutral molecule and the spin multiplicity of the ground electronic state is 1. Select "Neutral" in the box labeled "Total Charge" and pick "Singlet" in the "Multiplicity" box. These settings are the default values for "Total Charge" and "Multiplicity."
   
   



6. Since we intend to determine the atomic charges that best fit the electrostatic potential , check the "Elect.Charges" box in the "Compute:" row. We will want a list of the the molecular orbitals and orbital energies and a table of Mulliken and electrostatic charges. Check the "Orbitals & Energies" box and the "Atomic Charges" box in the "Print:" row to have this data "printed" to the output file. When the "Symmetry" box is checked (the default setting), the molecular symmetry of the starting geometry is used in the calculation.
   
   



7. Click the "OK" button to remove the "Step-up Calculations" window. Again, click "Setup" in the tool bar at the top of PC Spartan Pro window.
   
   



8. Select "Submit" in the pop-up menu. A "Save As" window will appear since we have yet to create a folder in which to store the results of the calculations. Open your (username) folder on the Z drive. If you wish, you can create a "Spartan" folder in your (username) folder and save your compuational work in this folder.
   
   



9. Name the file in which you wish to store the results and then click the "Save" button.
   
   



10. When the "PCPro" window appears, click the "OK" button.
    
    



11. When the optimization is completed, the "PCPro" window will reappear. Again, click the "OK" button.
    
    

1. Click "Display" in the tool bar at the top of PC Spartan Pro window and select "Output" from the pop-up menu. Enlarge the "Output" window. The output includes the type of calculation ( Geometry Optimization), the method of calculation (AM1), and the point group (D_3h) to which the model belongs.
   
   



2. The energy of the optimized structure is displayed just below the number of cycles required for convergence.
   
   



3. A table of molecular orbital energies and coefficients appears next. Each column in the table contains the energy of a MO in units of electron volts. Just below the energy is the the Mulliken symbol for the irreducible representation to which the molecular orbital belongs. The coefficients c_ji for the molecular orbital are listed beneath the symmetry label. c_i is a basis set function such as a valence AO. For example, molecular orbital #1, , has an energy of -21.76586 eV.
   
   



4. The electrostatic charges, dipole moment, and Mulliken charges are found at the end of the output file.
   
   

1. Click "Setup" in the tool bar at the top of PC Spartan Pro window and then select "Surfaces" from the pop-up menu.
   
   



2. Click the button at the bottom of the "Surfaces List" window.
   
   



3. When the "Add Surface" window appears, click the "Surface" pull-down menu.
   
   



4. Select "HOMO," the highest occupied molecular orbital.
   
   



5. Click the button on the "Add Surface" window.
   
   



6. Click the button to close the "Surfaces List" window and again,click "Setup" in the tool bar at the top of PC Spartan Pro window.
   
   



7. Select "Submit" from the pop-up menu. Each time the "PCPro" window appears, click the "OK" button.
   
   



8. Click "Display" in the tool bar at the top of PC Spartan Pro window and select "Surfaces" from the pop-up menu.
   
   



9. Click the yellow box next to "HOMO" in the "Surfaces List" window and then close the "Surfaces List" window.
   
   



10. The isosurface for the highest occupied molecular orbital (one of the e' MOs) appears in the "Solid" style.
    
    



11. Place the cursor on the isosurface and then click the left mouse button. Next, click "Display" in the tool bar at the top of PC Spartan Pro window and select "Properties" from the pop-up menu. A "Surface Properties" window will appear.
    
    



12. To select a different style, click on the "Style:" box and highlight "mesh" in the pull-down menu.
    
    



13. Click the button to close the "Surface Properties" window.
    
    



14. Place the cursor on the isosurface. Press and hold the left mouse button and then move the cursor up or down to rotate the isosurface on the x-axis and left or right to rotate the isosurface around the y-axis. Other mouse functions for orienting the isosurface in the window are available.
    
    



15. To remove the isosurface from the window, click "Display" in the tool bar at the top of PC Spartan Pro window and select "Surfaces" from the pop-up menu. Click the checked box next to "HOMO."
    
    

1. Click "Setup" in the tool bar at the top of PC Spartan Pro window and then select "Surfaces" from the pop-up menu. Click the button at the bottom of the "Surfaces List" window. When the "Add Surface" window appears, click the "Surface:" pull-down menu and select "density."
   
   



2. Next, click the "Property:" pull-down menu in the "Add Surface" window and select "potential."
   
   



3. Click the button in the "Add Surface" window, close the "Surfaces List" window, click "Setup" in the tool bar at the top of PC Spartan Pro window, and then select "Submit" from the pop-up menu.
   
   



4. Each time the "PCPro" window appears, click the "OK" button. Next, click "Display" in the tool bar at the top of PC Spartan Pro window and select "Surfaces" from the pop-up menu.
   
   



5. Click the yellow box next to "density" in the "Surfaces List" window and then close the "Surfaces List" window.
   
   



6. Place the cursor on the isodensity surface. Press and hold the left mouse button and then move the cursor up or down to rotate the isodensity surface on the x-axis. Other mouse functions for orienting the isodensity surface in the window are available.
   
   



7. Place the cursor on the isodensity surface and click the left mouse button. Next, click "Display" in the tool bar at the top of PC Spartan Pro window and select "Properties" from the pop-up menu. A "Surface Properties" window will appear. In the top left corner of the window you will find the maximum negative (-5.04753) and positive (35.9379) electostatic potentials. These values are represented on the isodensity surface with the colors red and blue. The electron density at any point on the isodensity surface is 0.002 electrons/bohr³. 1 bohr = 0.52917725 Å
   
   



8. To remove the isosurface from the window, click "Display" in the tool bar at the top of PC Spartan Pro window and select "Surfaces" from the pop-up menu. Click the checked box next to "density."