Date of Award

Fall 10-1-2021

Document Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Hammes-Schiffer, Sharon


Studies of molecular electrocatalysts often involve input from quantum chemical computations in the pursuit of catalyst design targeting several desirable features. To this end, conventional density functional theory (DFT) calculations have proven to be a good match with a reasonable balance between computational accuracy and cost. However, a multicomponent method that treats select nuclei on the same quantum mechanical level as electrons would be useful for a more proper treatment of nuclear quantum effects. Such a multicomponent DFT method has been developed in recent years within the nuclear-electronic orbital (NEO) framework. However, for the multicomponent method to be practically applied to large, chemically interesting systems, several functionalities were necessary. The NEO diagonal Born-Oppenheimer correction was calculated and shown to be small enough to validate the underlying Born-Oppenheimer-like separation between light and heavy nuclei. Analytical NEO Hessian expressions were derived and implemented, and they were utilized to identify transition states and generate multicomponent minimum energy paths. Lastly, the calculation of infrared spectra in the NEO framework was formulated and shown to produce accurate values compared to experiment. These developments have each been significant steps in preparing NEO-DFT for utilization in modeling molecular electrocatalysts.