Semiclassical Approaches to Complex Chemical Simulation in Real Time

Semiclassical (SC) theory offers a pedagogically rich connection between quantum and classical perspectives of nature, and, furthermore, is a promising approach to incorporating quantum effects into molecular dynamics simulations. However, a variety of numerical challenges associated with SC methods, such as the cumbersome search for special trajectories, or the integration of highly oscillatory functions (i.e. the SC ``sign problem"), generally renders SC theory impractical for all but very simple, low-dimensional systems. In this dissertation we derive a variety of mixed quantum-classical (MQC) representations of the real-time correlation function within the SC initial value representation (SC-IVR) using the modified Filinov filtration (MFF) technique. The most promising of these methods are subsequently tested on a number of low- and high-dimensional systems. Each of these methods have three significant advantages. (1) They offer a significant improvement upon the SC-IVR ``sign problem." (2) They offer mode-specific quantization in a dynamically consistent framework. And (3) they are significantly easier to implement than other leading SC-IVR methodologies. The extension of these methods to nonadiabatic systems is made as well. We conclude that, in future studies of a variety of non-equilibrium molecular systems, particularly those that exhibit strong nuclear quantum effects such as interference, the novel SC-IVR methods presented here should prove to be very powerful.

Name thesis:degree_name

Ph.D., Chemistry and Chemical Biology

Level thesis:degree_level

Doctor of Philosophy

Discipline thesis:degree_discipline

Chemistry and Chemical Biology

Grantor

Cornell University

Year dc:date.issued

2019

Author dc:creator

• Church, Matthew Steven

Committee members dc:contributor.committeemember

• Loring, Roger F.
• Ezra, Gregory Sion

• Quantum Mechanics
• Physical chemistry
• Computational Chemistry
• chemical physics
• initial value representation
• semiclassical dynamics
• theoretical chemistry

Language dc:language.iso

en_US

DOI

https://doi.org/10.7298/fys0-3128

Dc Identifier Other

ProQuest Submission ID: 11376
ProQuest Publication ID: 13878728

OAI identifier oai:identifier

oai:ecommons.cornell.edu:1813/67261