Study on the physical and chemical properties of dimethyl sulfoxide under the external electric field

Dimethyl sulfoxide (DMSO) is a versatile solvent used in many fields such as medicine and organic synthesis, whereas it is poisonous and harmful to human health. Physical and chemical properties, including bond length, dipole moment, total energy, frontier orbital energy, infrared absorption spectrum as well as the Raman spectrum of the DMSO molecule under an external electric field ranging from 0 to 0.03 atomic units were calculated by using the density functional theory (DFT) with the B3LYP/6-311G++(2d, p) basis set. According to the calculation, it has been found that as the external electric field increases, the two strongest infrared absorption peaks redshift and change in intensity. At the same time, a distinct new characteristic peak emerges in the Raman spectrum when the electric field is applied. Moreover, the Raman characteristic lines of DMSO were detected based on a self-designed Raman spectrometer. The potential energy curves under the increasing electric field were obtained by scanning the single-point energy along the S=O bond with the method B3LYP/6-311G (d, p). By fitting a linear curve between the potential barrier and the electric field, the intensity of the field corresponding to the zero potential barrier was computed. The results provide important theoretical references for further research about the DMSO's physical and chemical properties and indicate that the structure and properties of molecules change significantly under an external electric field.