3D Printed Potential and Free Energy Surfaces for Teaching Fundamental Concepts in Physical Chemistry

Teaching fundamental physical chemistry concepts such as the potential energy surface, transition state, and reaction path is a challenging task. The traditionally used oversimplified 2D representation of potential and free energy surfaces makes this task even more difficult and often confuses students. We show how this 2D representation can be expanded to more realistic potential and free energy surfaces by creating surface models using 3D printing technology. The printed models include potential energy surfaces for the hydrogen exchange reaction and for rotations of methyl groups in 1-fluoro-2-methylpropene calculated using quantum chemical methods. We also present several model surfaces created from analytical functions of two variables. These models include a free energy surface for protein folding, and potential energy surfaces for a linear triatomic molecule and surface adsorption, as well as simple double minimum, quadruple minimum, and parabolic surfaces. We discuss how these 3D models can be used in teaching different chemical kinetics, dynamics, and vibrational spectroscopy concepts including the potential energy surface, transition state, minimum energy reaction path, reaction trajectory, harmonic frequency, and anharmonicity.