Antisymmetric stretching vibration of sulfur dioxide and carbon disulfide modified by optical cavity

Abstract

For sulfur dioxide (SO2) and carbon disulfide (CS2) molecules in the optical cavity, we study the collective asymmetric Rabi splitting of vibrational strong coupling (VSC) and vibrational ultrastrong coupling (V-USC) between the antisymmetric stretching vibration mode of SO2/CS2 and the optical cavity mode using molecular dynamics simulations. We also study the modification effects of the optical cavity on their ground state bond lengths and rotation behavior. Through the simulation results, we find that although the asymmetric Rabi splitting phenomenon can both occur for SO2 and CS2 molecules, the promotion (or inhibition) effects on their upper polarons (UPs) are different with the increase of the coupling strength. In addition, we find that the relationship between polaron frequencies of SO2 molecules and cavity mode frequencies is consistent with that of CS2 molecules when the cavity mode frequency is highly positively detuned. However, the lower polaron(LP) of SO2 almost disappears and the LP's characteristic of CS2 is dominated by the cavity mode when the cavity mode frequency is highly negatively detuned. Finally, we find that there are obvious hole effects on the ground state rotation behavior of the two molecules. By comparing the different modification effects of the cavity on ground polar molecules (SO2 molecules) and ground non-polar molecules (CS2 molecules), we can not only further understand the differences between the vibrational modes of SO2 and CS2 molecules, but also provide important evidence that we may be able to change the chemical properties of SO2 and CS2 molecules by using VSC-V-USC in a reversible way. In addition, the cavity mode is used to regulate their UP and LP, which opens up a new way to control the physical and chemical properties of SO2 and CS2 molecules. Meanwhile, it also provides reliable information for vibration-polariton science, and provides comparable results for more complex experiments of light—matter coupling in the future.