Wednesday, August 31, 2022
Broadhead Center RM 068
Erin Johnson (Dalhousie University)
The development of dispersion corrections has allowed the application of density-functional theory (DFT) to a wide range of problems in materials science. One such problem is molecular crystal structure prediction (CSP) of a given compound from its molecular diagram. CSP requires accurate and efficient evaluation of energy differences between candidate structures to determine the most thermodynamical stable form(s), which should be seen experimentally. Identification of likely crystal structures further allows prediction of emergent properties, such as charge transport and photoluminescence. Another example where the advent of dispersion corrections was an essential advance is the study of layered materials, such as graphene and transition-metal dichalocogenides (TMDCs). The 2D electrides are a particularly novel class of layered materials, in which the positively charged atomic layers are separated by interstitial regions of confined electrons. In this talk, I will highlight recent applications of DFT to molecular crystal structure prediction, with a focus on helicene compounds, which have potential utility as organic electronics. I will also present a study of electride materials and their insertion at metal-TMDC interfaces to improve charge transport. Finally, I will discuss the implementation of our exchange-hole dipole moment (XDM) dispersion model into the FHI-aims code to enable computational modeling of much larger systems than was previously feasible.