Abstract: The author obtained the ground states geometry of C₈H₁₄O molecule under different intense electric fields ranging from -0.008 0 to 0.002 5 based on the method of density functional theory DFT/B3P86 at the 6-311++G(2-df-) basis set level. The author studied the effect of the same electric field intensities on the excitation energies and oscillator strengths of the optimized C₈H₁₄O molecule by using the timedependent density functional theory (TD-DFT) method. The calculation results show that the molecular geometry is influenced by the electric field intensity. The excitation energies decrease as the increase of the electric field intensity, indicating that the C₈H₁₄O molecule is easy to be dissociated and excited under the action of electric field intensity.

Key words: timedependent density functional theory (TD-DFT), excited state, electric field, cyclooctanone molecule