▎ 摘　　要

We theoretically study the band structure and optical conductivity of twisted double bilayer graphene with an applied vertical electric field. We consider two different arrangements, AB-AB and AB-BA, which host dissimilar optical gaps and absorption edges in the absence of electric field. In the presence of electric field, the opening energy gaps for the two systems exhibit different magnitude as well as the optical gaps, which can be easily observed in the optical conductivity spectrum. We also calculate the bandwidths of flat bands at the electron side with a wide range of twist angles, and demonstrate that extremely narrow bandwidths can be achieved by tuning the applied electric field. Moreover, for twist angles from 1 degrees to 1.3 degrees, the bandwidths of the two systems show an opposite behavior under low electric field. These results can be helpful to explore the tunable optical property and correlated electron states in the twisted double bilayer graphene. (C) 2021 Published by Elsevier B.V.