Spectra and excitation properties of (AlP)₈: Effect of external electric fields

Abstract

On the basis of density functional theory (DFT), the geometry and infrared spectrum of the (AlP) 8 cluster have been calculated under external electric fields (EEFs). In addition, on the basis of time-dependent DFT, the ultravioletvisible absorption spectra, oscillator strengths, wavelengths, and hole-electron orbits of the first 20 excited states have been calculated. Under EEFs, the energy of (AlP) 8 gradually decreases, the dipole moment increases, and the molecular configuration significantly changes. In the infrared spectrum, the vibration frequency corresponding to the stretching vibration of the Al-P bond decreases, and a red shift occurs. With increasing EEF, the infrared spectrum splits and shows an obvious Stark effect; the ultraviolet absorption intensity is enhanced, and the molecular excitation energy decreases. Additionally, the excitation wavelength increases with increasing EEF. It is conclusively shown that the (AlP) 8 cluster is easily excited under an EEF. Separation of the holes and electrons of the (AlP) 8 cluster is obvious. Theoretical investigation of the spectra and excitation properties of (AlP) 8 is an important step toward a comprehensive understanding of the effects of EEFs on the molecular structure, stability, and dynamics.