The particle-in-a-box (PIB) model is a quintessential yet abstract concept for Physical Chemistry. Students often find the model hard to understand due to the mathematical complexity of the model and the limited perceived relevance. Traditionally, students probe the PIB model by measuring the UV-vis absorption of conjugated carbocyanine dyes. This experiment links chain length to π-π* transition energies via an analytical formula in comparison to experimental spectra. To deepen engagement and conceptual understanding, an updated version of the experiment integrates computational chemistry with classic laboratory techniques. In this new version of the PIB experiment, students collect data through three routes: 1) compute the UV-vis absorption spectra using timedependent density functional theory (TDDFT), 2) collect experimental UV-vis spectra using a spectrophotometer, and 3) solve the PIB model in an infinite and finite well with Python scripts to predict theoretical absorption peaks. Students can connect molecular orbital theory to the restriction of electron motion to discrete energy levels by comparing the computationally determined λmax to the experimentally collected spectra. Additionally, the use of Python introduces valuable skills in coding, data analysis, and visualization. Together, these elements create a multifaceted learning experience that reinforces core physical chemistry concepts through modern computational tools and showcases how students are engaged with Physical Chemistry via an appreciation of computational chemistry and modeling.
This repository has the information for a Physical Chemistry Lab using TDDFT to visualize the connection between MO theory, UV-vis absorption, and the paritcle-in-a-box models (infinite and finite wells). Handouts and Python codes that will run on Google Colab are included.
Patel, P.* Modernizing Physical Chemistry: Integrating Computational Chemistry, the Finite Well, and Python Data Visualization in the Particle-in-a-Box Experiment. In Engaging Students in Physical Chemistry, Volume 2; ACS Symposium Series; American Chemical Society, 2025; Vol. 1515, pp 261–278. https://doi.org/doi:10.1021/bk-2025-1515.ch017.