In order to analyze the influence of external electric field on the performance of insulating paper from the microscopic point of view

the B3 LYP/6-31 G（d）basis group is used to optimize the structure of the cellobiose molecule. The ground state structure

frontier orbital energy

energy gap

infrared spectrum

Mulliken charge population and bond level of cellobiose were analyzed under different external electric fields. The calculation results show that as the external electric field increases

the cellulose molecular chain first stretches and then shrinks. The total energy of the molecule decreases

the potential energy increases

the dipole moment and the polarizability increase;the HOMO energy increases

the LUMO energy decreases

and the energy gap decreases

resulting in an increase in molecular activity and a decrease in stability. The C-O stretching vibration absorption peak and the asymmetric stretching vibration absorption peak of the glycosidic bond C-O-C in the pyran ring are both red shift

causing the vibration to become unstable;the nucleophilic site and the electrophilic site are transferred to the secondary hydroxyl group at the left and right ends of the cellobiose molecule respectively

and the secondary hydroxyl group bond energy at the right end is lower. So the glycosidic bond

the pyran ring and the secondary hydroxyl group in the cellobiose molecule are more easily destroyed under external electric field than other positions

and the critical breakdown electric fieldintensityis 13.369 GV/m.