Comparative Study of Vibrational Raman Optical Activity with Different Time-Dependent Density Functional Approximations: The VROA36 Database

A new database, VROA36, is introduced
to investigate the performance
of computational approaches for vibrational Raman optical activity
(VROA) calculations. The database is composed of 36 molecules with
known experimental VROA spectra. It includes 93 conformers. Normal
modes calculated with B3LYP-D3­(BJ)/def2-TZVP are used to compute the
VROA spectra with four functionals, B3LYP-D3­(BJ), ωB97X-D, M11,
and optimally tuned LC-PBE, as well as several basis sets. SimROA
indices and frequency scaling factors are used to compare calculated
spectra with each other and with experimental data. The four functionals
perform equally well independently of the basis set and usually achieve
good agreement with the experimental data. For molecules in near-
or at-resonance conditions, the inclusion of a complex (damped) linear
response approach is important to obtain physically meaningful VROA
intensities. The use of any of the tested functional approximations
with the def2-SVPD Gaussian-type basis set, or a basis of similar
flexibility, can be recommended for efficient and reliable theoretical
VROA studies.