  Recent experiments have probed the chiral properties of semiconductor
nanocrystal (NC) quantum dots (QDs), but understanding the circular dichroism
lineshape, excitonic features, and ligand induction mechanism remains a
challenge. We propose an atomistic pseudopotential method to model chiral
ligand passivated QDs, computing circular dichroism (CD) spectra for CdSe QDs
(2.6 - 3.8 nm). We find strong agreement between calculated and measured
spectra, predicting consistent bisignate lineshapes with decreasing CD
magnitude as size increases. Our analysis reveals the origin of bisignate
lineshapes, arising from nondegenerate excitons with opposing angular momenta.
We also explore the impact of chiral ligand orientation on QD surfaces,
observing changes in optical activity magnitude and sign. This orientation
sensitivity offers means to distinguish ordered from disordered ligand
configurations, facilitating the study of order-disorder transitions at
ligand-QD interfaces.
