Electric field control of electronic properties in a fluorinated ferroelectric liquid crystal: a DFT/TD-DFT study

Fluorinated ferroelectric liquid crystals are promising materials for electro-optical devices, yet the molecular-level response to electric fields remains poorly understood. This DFT/TD-DFT study investigates the fluorinated compound R-C12F2 under static electric fields up to 16.5 V $·$ nm $_{}^{-1}$ . We report two notable phenomena: a staircase-like evolution of the dipole moment and a field-induced overlap between the HOMO and LUMO orbitals, indicating significant electronic reorganization and discrete molecular reorientations. These findings reveal strong anisotropic field-matter interactions governed by molecular architecture.

Geometry optimization and property calculations were performed using Gaussian 16 with the CAM-B3LYP functional and 6-31G(d,p)/6-31 $_{}^{++}$ G(d,p) basis sets. Excited-state properties (UV-Vis, ECD) were computed via TD-DFT, and vibrational spectra (IR, VCD, Raman) were obtained at the same level. Static electric fields (0-16.5 V $·$ nm $_{}^{-1}$ ) were applied along the cartesian axes. An ultrafine integration grid and tight optimization criteria ensured numerical accuracy.