Study on the physical properties of molecule LiF in external electric field

In this paper,the ab initio method of quantum mechanics is used to optimize the geometric structure of the ground state of LiF molecule with the DFT B3LYP method and 6-311basis in electric fields ranging from -0.015 to 0.015 a.u. The effects of external electric fields on the system energy, bond distance, dipole moment,energy levels, HOMO-LUMO gaps, charge distribution and the infrared spectrum are studied. The results show that the molecular bond distance, dipole moment, HOMO-LUMO gaps and the total atomic charges gradually increase with the increase of the external electric field along the molecular axis Z. At the same time, the total energy of the molecule, frequency and IR intensity decrease and the energy of dissociation becomes smaller with the increase of the external electric field.