Join us for the Physics Condensed Matter Seminar at 2:30 pm
Title: "Mechanically Imaging the Chemical Bond"
Abstract:
About a half century ago, Richard Feynman noted that characterizing the microscopic structure of materials would be a lot easier if one could just look and see where the atoms were. In some ways, “seeing atoms in a molecule” is now feasible fulfilling Feynman’s suggestion.
In particular, recent advances in atomic force microscopy have mechanically rendered images of chemical bonds with an unprecedented resolution. These advances offer the possibility of imaging the subatomic structure of molecules. Still, fundamental questions remain about interpreting such images. While most features in the measured images have a close correspondence to the atomic structure of a given specimen, some cannot be so interpreted.
In order to simulate an atomic force image and address such questions, one must calculate accurate interatomic forces between the specimens and the probe as a function of the tip height. The required calculations are computationally intense as they may involve thousands of atoms for a like number of different geometries. Such calculations are traditionally outside of our capability, even with contemporary computational platforms. I will illustrate how new algorithms for simulating atomic force microscopy can address these computational hurdles and result in images that often replicate measured bond properties in subatomic detail for a variety of complex molecular species.
References:
P. Cheng, D. Fan, A. Selloni, E.A. Carter, C.B. Arnold, D. C. Dankworth, S. P. Rucker, J.R. Chelikowsky, Y. Zhang, and N. Yao: “How Strong Is a Dative Bond Measured at the Single-Molecule Level?” Nat. Comm. 12, 5635 (2021).
D. Fan and J.R. Chelikowsky: “Atomic Fingerprinting Using Noncontact Atomic Force Microscopy,'' Small 17, 2102997 (2021).
Join Zoom Meeting https://berkeley.zoom.us/j/99982021890?pwd=OTMyd3cwMGp5Tk9QTW1vNk9EMDJNZz09
Meeting ID: 999 8202 1890 Passcode: 954439
Location: virtual (zoom)
Speaker: James R. Chelikowsky
Affiliation: University of Texas at Austin