Theoretical Investigation of the Defect Position Effect on Optical Functionality of N and B Doped Graphene

In general, dipole moment differences and (hyper) polarizability indices are used to describe the optical functionality of chemical compounds. In the presence of a homogenous week electric field, energy of a system is a functional of the applied electric field. The components of dipole moment, polarizability, and first-order hyperpolarizability are the coefficients in the Taylor series expansion of the energy [1,2]. In this research, the total static dipole moment (μ), the mean polarizability , the anisotropy of the polarizability (α), and the first-order hyperpolarizability (β) parameters have been calculated for normal graphene and related B and N doped species. The dipole moment of the parent molecule is zero. However, defect causes a significant shift in dipole moment of graphene nanoflake. B doped species have a higher value of dipole moment, comparing with N doped ones. When the defect position alters from the center to the edge of the graphene, the difference between the μ value of B and N doped molecule become more and more. B doped species have higher and α values than the relative N doped ones. For both B and N doped species, the marginal defect position is accompanied with the highest and α values. Although the β value of the parent molecule is almost zero, defected graphenes have remarkable β. As the defect position shifts to the marginal region, the β value increases. A considerable point is that, N and B defect in inner positions have a similar effect on the β value of molecule.