Benjamin Eller (Assoc)

My Ph.D. research focused on the theoretical and computational modeling of ground states and excited electronic states (i.e. excitons) of ultrashort segments of single-wall carbon nanotubes (SWCNTs) < 15 nm in length (essentially SWCNT quantum dots). I studied the intrinsic SWCNTs themselves, as well as nanotubes functionalized with sp³-carbon defects that trap and localize exciton states, augmenting their optical properties. To study these materials, I combined density functional theory (DFT), time-dependent DFT, and physical arguments applied to idealized molecular models.
 

I theoretically demonstrated the potential for creating fluorescent metallic nanotubes using sp³ defects and made a prediction of unconventional length-dependence of excitonic absorption energies in ultrashort SWCNTs, a result that challenges existing pictures of quantum confinement in SWCNTs. Most recently, I have demonstrated a unification of theoretical organic chemistry (Clar's sextet-maximization principle for polycyclic hydrocarbons) and topological invariants of graphenic structures. In doing so, a molecular picture of fluorescence quenching in ultrashort SWCNTs was developed, that also explains how the sp³ functionalization of ultrashort SWCNT edges creates bright fluorescent ultrashort nanotubes (FUNs) out of the typically non-fluorescent ultrashort SWCNTs. 

Much of my PhD research has been accomplished with the help of a Python module that I developed for programmable molecular generation, called ChemG. I have published ChemG for others to use (https://github.com/beneller/ChemG), and I plan on continuing its development for use in studying FUNs and materials more broadly. This module is well-suited for studying structures that depart from conventional crystals, such as clusters, disordered systems, systems with defects, and finite nanostructures with designer geometries.

As a Guest Researcher at NIST, I have turned my attention to problems relevant to SWCNT sorting methods, and the use of exceptionally pure SWCNTs for characterizing their optical properties to aid in the development of SWCNT-based sensing technologies.

https://orcid.org/0000-0002-6538-4768

http://linkedin.com/in/benjamin-eller-603989356

https://beneller.github.io/

2024: Summer Research Fellowship, UMD.