The virtual multifrequency spectrometer: a new paradigm for spectroscopy

Abstract

On going developments of hardware and software are changing computational spectroscopy from a strongly specialized research area to a general tool in the inventory of most researchers. Increased interactions between experimentally-oriented users and theoretically-oriented developers of new methods and models would result in more robust, flexible and reliable tools and studies for the systems of increasing complexity, which are of current scientific and technological interest. This is the philosophy behind this review, which presents the development of a so-called virtual multi-frequency spectrometer (VMS) including state-of-the-art approaches in a user-friendly frame. The current status of the VMS tool will be illustrated by a number of case studies with special reference to infrared and UV-vis regions of the electro-magnetic spectrum including also chiral spectroscopies. Only the basic theoretical background will be provided avoiding explicit equations as far as possible, and pointing out the most recent advancements beyond the standard rigid-rotor harmonic-oscillator model coupled to vertical electronic excitation energies.

Computational simulation of vibrationally resolved spectra for spin‐forbidden transitions

“…The cc‐pVDZ basis set was used for camphorquinone in all calculations, whereas the 6‐31G*/LANL2DZ basis set with pseudopotential on iridium was used for Ir complexes. sRGB colors have been calculated by the color utility present in VMS . Cube file visualization and manipulation have been performed with Caffeine …”

Aiming at an accurate prediction of vibrational and electronic spectra for medium‐to‐large molecules: An overview

“…Molecular properties are commonly probed with a wide panel of spectroscopies, which can be combined to offer a unique picture, reflection of the property, its environment, and the experimental conditions . The wealth of information contained in the recorded spectrum or spectra can become complex to analyze in a purely phenomenological way and theoretical models can provide a valuable aid in understanding the origin of the features observed in the band‐shapes . As a matter of fact, the predictive and interpretative power of computational spectroscopy has been clearly demonstrated already for small molecular systems in the gas phase, by comparison with the most sophisticated experimental techniques .…”

“…Hence, to facilitate the simulation and interpretation of multiple spectra, several conditions need to be met. A first challenge is to provide a simple interface, lowering the barrier to the broad adoption of state‐of‐the‐art methods able to produce accurate data for the problems at hand . This can be achieved by automatizing most aspects of the calculations.…”

“…A second requirement is to be able to choose the most appropriate methodology based on the size and topology of the molecular system under study, the target accuracy, and the complexity of the environment and its possible effects on the system. In this article, we will focus on cost‐effective methods, suitable for the simulation of electronic or vibrational spectra of medium‐to‐large molecular systems, ranging from half‐a‐dozen to more than a 100 atoms, and how they can be integrated within a unified platform, that we will call the virtual spectrometer . While those methods are primarily intended for semirigid molecules, their extension to support also more flexible systems will be discussed.…”

Integrated QM/polarizable MM/continuum approaches to model chiroptical properties of strongly interacting solute–solvent systems

“…This is reflected in the computational methodologies which have been developed so far, which are mainly interested in getting an accurate reproduction of peak positions (infrared/Raman wavenumbers, UV‐Vis transition energies, NMR chemical shieldings, etc. ), reserving instead much less attention to spectral intensities . In case of chiroptical properties/spectroscopies, an opposite situation occurs, in fact not only the absolute value but also especially the sign of the spectroscopic response is the most relevant information taken from the spectra.…”