This is the fourth in a series of exercises used to teach computational chemistry. It has been adapted, with permission, from a Shodor CCCE exercise (http://www.computationalscience.org/ccce). It uses the WebMO interface for drawing structures and visualizing results. WebMO is a free web-based interface to computational chemistry packages (www.webmo.net).
In this exercise, students perform coordinate scans to explore how changes in bond length, bond angle, and dihedral angle can affect molecular energy. The results allow them to visualize the relationship between the geometry change and molecule's energy.
The exercise provides detailed instructions, but does assume that students are familiar with WebMO and can build molecules and set up calculations.
Students will be able to:
- Calculate and visualize the potential energy surface of a diatomic molecule.
- Calculate and visualize the energy changes in a small molecule during bending.
- Calculate and visualize the changes in energy when a small molecule undergoes conformational changes.
Students need access to a computer, the internet, and WebMO (with Mopac and Gaussian).
I use this as an in-class exercise. Students bring their own laptops and access our institution's installation of WebMO through wifi.
This exercise usually takes less than a 50 minute class period. Students record their answers directly onto their handouts, and I collect the handouts either at the end of class or at the beginning of the next class.
Student work is typically complete and correct because they have completed the exercise in class and received feedback as they worked.