Physics Seminar

This talk presents current work and proposes future developments in the creation of practical quantum methods for studying nanotechnologically important systems. After a brief introduction discussing the computational and methodological limitations of applying current quantum chemical methods to systems on the nanoscale, the results of two previous studies are presented from work conducted at Rice University in the Scuseria Group. First, calculating the polarizability of carbon single wall and coaxial nanotubes will be discussed. This work resulted in the discovery of interesting shielding properties of coaxial (and by extension, all multi-wall) nanotubes. This example indicates the importance of including quantum effects in computationally modeling nanotechnologically important systems. The second study to be presented is calculating enthalpies of formation for a variety of molecules starting from reference states other than infinitely separated atoms, which results in enhanced accuracy for many theoretical methods, even with small basis sets. This work provides a more fair evaluation of quantum chemical method’s efficacy than that found in previous works, and indicates the potential of these computationally inexpensive methods, as using non-atomic reference states can remove even qualitative errors in predicting enthalpy of formation. Time permitting, the talk will conclude with proposals for future development of methods which are practical for nanoscale systems and which include important forces neglected in the current generation of computationally efficient methods.