eprintid: 35704 rev_number: 11 userid: 8327 dir: disk0/00/03/57/04 datestamp: 2019-01-30 22:38:57 lastmod: 2019-01-30 22:38:57 status_changed: 2019-01-30 22:38:57 type: thesis_degree metadata_visibility: show contact_email: michael.hartmann121@gmail.com eprint_status: archive creators_name: Hartmann, Michael creators_email: mjh124@pitt.edu creators_id: mjh124 title: Computational Studies of Structure and Surface Reactivity in Metal Nanoclusters ispublished: unpub divisions: sch_as_chemistry full_text_status: public keywords: Nanoparticle, Surface Chemistry, Density Functional Theory, Magnetism, Optoelectronic abstract: Metal nanoparticles exhibit physical and chemical properties unique to their length scale that have the potential to shape next generation technologies. The large structural and chemical space that determines nanoparticle properties requires feedback between computational and experimental studies to drive the discovery of both new architectures and target properties of these systems. This dissertation describes the application and development of theoretical methods to study metal nanoparticle electronic structure, developing new structure-property relationships and new concepts that govern nanoparticle behavior while connecting theoretical insight with laboratory observations. In Chapter 1, the dissertation is introduced by detailing how the connection between geometry and electronic structure has shaped the way we teach and understand chemistry across length scale, and projects these concepts onto the 1-3 nm length scale where traditional descriptors of electronic structure break down. In Chapter 2, the optoelectronic impact of alloying Cu with a Au nanocluster is studied, revealing how atomic descriptors and position of the heteroatom determine optical absorption in [Au25(SR)18] , providing an easily accessible experimental readout of electronic structure. Building on hypotheses tested in Chapter 2, Chapter 3 explores the size dependence of Cu/Au alloying. Here, the atom concentration and composition architecture are key parameters predicted to drive the emergence of plasmonic behavior in Au144-xCux(SR)60 nanocluster. In addition to the composition dependence of nanoparticle properties, the surface chemistry is known to dominate overall nanocluster electronic structure. In Chapter 4, both the type and specific molecular descriptors of the ligand were shown to impact the total magnetic moment of Co13 and Co55 model nanoclusters. Chapter 5 extends these concepts of surface chemistry to address the size dependent evolution of the ligand mediated magnetic properties in CoN nanoclusters, demonstrating how energy level alignment and orbital symmetry contribute to size dependent trends. Finally, Chapter 6 describes a reduced scaling computational method that improves the approximation of mean field excited state energy predictions, increasing the size and complexity of systems that can be treated with high accuracy. date: 2019-01-30 date_type: published pages: 182 institution: University of Pittsburgh refereed: TRUE etdcommittee_type: committee_cochair etdcommittee_type: committee_cochair etdcommittee_type: committee_member etdcommittee_type: committee_member etdcommittee_type: committee_member etdcommittee_name: Millstone, Jill etdcommittee_name: Lambrecht, Daniel etdcommittee_name: Jordan, Kenneth etdcommittee_name: Hutchison, Geoffery etdcommittee_name: Mpourmpakis, Giannis etdcommittee_email: jem210@pitt.edu etdcommittee_email: lambrecht@pitt.edu etdcommittee_email: jordan@pitt.edu etdcommittee_email: geoffh@pitt.ed etdcommittee_email: gmpourmp@pitt.edu etd_defense_date: 2018-11-15 etd_approval_date: 2019-01-30 etd_submission_date: 2018-12-05 etd_release_date: 2019-01-30 etd_access_restriction: immediate etd_patent_pending: FALSE thesis_type: dissertation degree: PhD citation: Hartmann, Michael (2019) Computational Studies of Structure and Surface Reactivity in Metal Nanoclusters. Doctoral Dissertation, University of Pittsburgh. (Unpublished) document_url: http://d-scholarship-dev.library.pitt.edu/35704/7/hartmannmj_ETD_final_resubmit.pdf