20 May 2019

CompChem 01: Creating a Basis Set

In-Class Activity

Submitted by Joanne Stewart, Hope College

This is the first 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).

In the exercise, students learn about simple Gaussian-type basis sets. In an Excel spreadsheet, they compare the Slater function for a 1s orbital to the combination of one, two, or three Gaussian functions. They are also introduced to the Basis Set Exchange website (https://bse.pnl.gov/bse/portal).


File Student handout for basis set exercise242.29 KB
Learning Goals: 

After completing this exercise, students will be able to:

  1.  Explain why Gaussian-type orbitals (GTOs) are used instead of Slater-type orbitals (STOs) in computational chemistry.
  2.  Use Excel to model the hydrogen STO with GTOs.
  3.  Explain why combining multiple GTOs produces a better approximation of an STO.
  4.  Find alpha values for the STO-3G basis set in an online database.
Equipment needs: 

Students need access to a computer, the internet, and Excel. I initially taught this part of the course in a computer lab, but last year all of the students were able to bring their own laptops. I bring an extra laptop to class just in case.

Implementation Notes: 

All of the students had some experience with Excel in their general chemistry course. However, entering the complicated equations into Excel is challenging for many of them. I have found it most effective to simply allow them to help one another with this.

They are typically able to make the graphs without extra assistance, but I walk around the class and help as needed.

Time Required: 
30 minutes
Evaluation Methods: 

I ask the students to bring printed copies of their graphs and answers to the questions in the student handout to the next class. I collect these and check them for completeness (credit/no credit). 

Evaluation Results: 

Because the students completed the exercise during the previous class, their work is typically complete and correct.

Creative Commons License: 
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