Vibrational Angular Momentum in Molecules Driven by Dynamical Effects*

The angular momentum of static vibrational modes in solids manifests, among others, at the Brillouin zone corners of non-centrosymmetric crystal lattices and in ionic crystals in presence of an external magnetic field.
In this work, we show that also in molecules, under certain conditions, the angular momentum of vibrational modes can be nonzero. In particular we enforce the dynamical scheme of linear response to assess the vibrational properties of molecules.
In this framework we prove that an intrinsic angular momentum can emerge in the optical modes of non-collinear magnetic clusters as a result of the electron-phonon interaction.
These vibrational modes are suitable for detection in polarized Raman spectroscopy.