How lithium atoms affect the first hyperpolarizability of BN edge-doped graphene

How do lithium atoms affect the first hyperpolarizability (β 0 ) of boron–nitrogen (BN) edge-doped graphene. In this work, using pentacene as graphene model, Li n @BN-1 edge-doped pentacene and Li n @BN-2 edge-doped pentacene ( n = 1, 5) were designed to study this problem. First, two models (BN-1 edge-doped pentacene, and BN-2 edge-doped pentacene ) were formed by doping the BN into the pentacene with different order, and then Li@BN-1 edge-doped pentacene and Li@ BN-2 edge-doped pentacene were obtained by substituting the H atom in BN edge-doped pentacene with a Li atom. The results show that the first hyperpolarizabilities of BN-1 edge-doped pentacene and Li@BN-1 edge-doped pentacene were 4059 a.u. and 6249 a.u., respectively; the first hyperpolarizabilities of BN-2 edge-doped pentacene and Li@BN-2 edge-doped pentacene were 2491 a.u. and 4265 a.u., respectively. The results indicate that the effect of Li substitution is to greatly increase the β 0 value. To further enhance the first hyperpolarizability, Li 5 @ BN-1 edge-doped pentacene and Li 5 @BN-2 edge-doped pentacene were designed, and were found to exhibit considerably larger first hyperpolarizabilities (β 0 ) (12,112 a.u. and 7921a.u., respectively). This work may inspire further study of the nonlinear properties of BN edge-doped graphene.