Evaluation of molecular polarizability and of intensity carrying modes contributions in circular dichroism spectroscopies

Year: 2019

Authors: Zanchi C., Longhi G., Abbate S., Pellegrini G., Biagioni P., Tommasini M.

Autors Affiliation: Politecn Milan, Dipartimento Chim Mat & Ingn Chim, Piazza Leonardo da Vinci 32, I-20133 Milan, Italy;‎ Univ Brescia, Dipartimento Med Mol & Traslazionale, Viale Europa 11, I-25123 Brescia, Italy; CNR, INO, CSMT Via Branze 45, I-25123 Brescia, Italy; Politecn Milan, Dipartimento Fis, Piazza Leonardo da Vinci 32, I-20133 Milan, Italy

Abstract: We re-examine the theory of electronic and vibrational circular dichroism spectroscopy in terms of the formalism of frequency-dependent molecular polarizabilities. We show the link between Fermi’s gold rule in circular dichroism and the trace of the complex electric dipole-magnetic dipole polarizability. We introduce the C++ code polar to compute the molecular polarizability complex tensors from quantum chemistry outputs, thus simulating straightforwardly UV-visible absorption (UV-Vis)/electronic circular dichroism (ECD) spectra, and infrared (IR)/vibrational circular dichroism (VCD) spectra. We validate the theory and the code by referring to literature data of a large group of chiral molecules, showing the remarkable accuracy of density functional theory (DFT) methods. We anticipate the application of this methodology to the interpretation of vibrational spectra in various measurement conditions, even in presence of metal surfaces with plasmonic properties. Our theoretical developments aim, in the long run, at embedding the quantum-mechanical details of the chiroptical spectroscopic response of a molecule into the simulation of the electromagnetic field distribution at the surface of plasmonic devices. Such simulations are also instrumental to the interpretation of the experimental spectra measured from devices designed to enhance chiroptical interactions by the surface plasmon resonance of metal nanostructures.


Volume: 9 (21)      Pages from: 4691-1  to: 4691-25

More Information: This research was funded by the Italian Ministry of Education, Universities and Research (MIUR) through the PRIN 2015 program (Project No. 2015FSHNCB “Plasmon-enhanced vibrational circular dichroism”).
KeyWords: computational molecular spectroscopy; density functional theory; VCD intensity; dissymmetry factor g(omega); Intensity Carrying Modes (ICM)
DOI: 10.3390/app9214691

Citations: 5
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