Modeling Exercise # 3 -- continued

Task 3: Optimize the geometry and compute the heat of formation of water using MOPAC (AM1 and PM3)

Time: 4 minutes

1. Optimize the geometry and compute the enthalpy of formation of water using AM1
1. Open the water molecule saved for MOPAC AM1: File|Open "water-AM1".
2. Select Experiment|New
3. In the Property of: box, select chemical sample.
4. in the Property box, select optimized geometry.
5. in the Using box select AM1 geometry.
6. Click Start.
2. Record the value of the heat of formation of the molecule found in the experiment status box.
3. Record the computation time found in the experiment status box.
4. Close the experimental status box and the experiment box and save the file:  File|Close
5. Optimize the geometry and compute  enthalpy of formation of water using PM3
   1. Open the water molecule saved for MOPAC PM3: File|Open  "water-PM3".
   2. Repeat steps 1b through 1d above.
   3. In the Using box select PM3 geometry.
   4. Click Start.
6. Record the value of the heat of formation found in the experiment status box.
7. Record the computation time found in the experiment status box.
8. Close the experimental status box and the experiment box and save the file:  File|Close

In the next lesson you will optimize the geometry and compute the enthalpy of formation of water using DFT.