Study of Density Functional Theory (DFT) for Raman Spectra of CH₃OLi and CH₃CH₂OLi

Molecular configurations of CH₃OLi and CH₃CH₂OLi were structured based on the previous study that lithium atom and oxygen atom are directly joined by O-Li bond in alkoxy lithium (ROLi). Neither experimental nor theoretical Raman spectra of CH₃OLi and CH₃CH₂OLi have been reported up to now. In the present paper, DFT method at the B3LYP/ 6-31G(d,p) level was used to optimize molecular configurations of CH₃OLi and CH₃CH₂OLi, obtaining each corresponding equilibrium configuration. Vibration frequencies and Raman spectra of these two molecules were calculated based on equilibrium configuration. The vibration frequencies of obtained calculated results were analyzed by normal coordinate analysis. Besides, the Raman vibration modes of CH₃OLi and CH₃CH₂OLi were assigned according to potential energy distribution of each vibration frequency, which will provide theoretical basis for experimental workers to analyze the components of solid electrolyte interface film (SEI film) of lithium ion battery.