Date of Award
Spring 2022
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Chemistry
First Advisor
Hammes-Schiffer, Sharon
Abstract
Through treating select nuclei quantum mechanically at the same level as electrons, the nuclear-electronic orbital (NEO) method inherently captures the important nuclear quantum effects of the system. Without the Born-Oppenheimer (BO) separation between electrons and select nuclei, vibronic states are described naturally. Treating protons quantum mechanically within the multicomponent density functional theory (DFT) framework introduces an additional functional to describe electron-proton correlation (epc). This dissertation introduces an epc functional based on the generalized gradient approximation (GGA), which can provide accurate protonic densities and energies. Electron-proton vibronic excitations can be calculated through NEO time-dependent density functional theory (NEO-TDDFT). This Dissertation further introduces NEO-TDDFT analytical gradients, which allow geometry optimizations and adiabatic dynamics on the excited vibronic surfaces. As nonadiabatic effects can become important for systems involving photoinduced proton transfer, real-time NEO-TDDFT (RT-NEO-TDDFT) with Ehrenfest dynamics is introduced to account for the nonadiabatic effects in a mean-field way. By including proton density delocalization and zero-point energy during geometry optimizations and dynamics, NEO-DFT and NEO-TDDFT offer an efficient framework to study a wide range of chemical and biological systems involving processes such as proton-coupled electron transfer and photoinduced proton transfer.
Recommended Citation
Tao, Zhen, "Nuclear-Electronic Orbital Density Functional Theory for Quantizing Protons" (2022). Yale Graduate School of Arts and Sciences Dissertations. 935.
https://elischolar.library.yale.edu/gsas_dissertations/935