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Erin Johnson

Chemistry Weekly Seminar - Erin Johnson, Dalhousie University

Erin Johnson, Professor in the Department of Chemistry, Dalhousie University, will present a seminar at 1:30 pm in Thorvaldson 159.



Molecular crystal structure prediction and comparison


Accurate and efficient computation of relative energies of molecular crystal polymorphs is of central importance for solid-state pharmaceuticals and in development of new molecular materials. In this talk, we show that pairing GGA and hybrid density functionals with the exchange-hole dipole moment dispersion correction provides excellent performance for binding energies of small molecular dimers, exfoliation energies of layered materials, absolute and relative lattice energies of molecular crystals, and for the energy ranking step of molecular crystal structure prediction. We also present our variable-cell powder difference (VC-PWDF) method, which allows rapid and reliable identification of matches to experimental polymorphs from computed crystal-energy landscapes. Finally, we extend VC-PWDF to allow direct comparison of collected powder diffractograms of unknown polymorphs to both experimental and in silico-generated crystal structures. This method is shown to correctly identify the most similar crystal structure to both moderate and low quality experimental powder diffractograms for a set of 7 representative organic compounds and should allow rapid identification of new polymorphs from solid-form screening studies, without requiring single-crystal analysis.

Date:    Friday, November 3

Time:    1:30 pm

Place:    Thorvaldson 159

Note:    Professor Johnson will join remotely.