The Account of Molecular Multipole Moments in the Study of the Effect of Locally Anisotropic Polarizable Deformable Medium on the Nonlinear Optical Response of Incorporated Chromophore

The model suggested earlier by the author and allowing to describe the effect of locally anisotropic polarizable polymer matrix on the nonlinear optical response of incorporated chromophore is generalized to the case when a chromophore charge distribution is approximated by the multipole expansion including the terms up to octupole. The analytical formula for the local electric field, affecting the chromophore in a polymer electret, is obtained as a solution of electrostatic problem for a molecule in an ellipsoidal cavity, with corresponding boundary conditions taken into account. The approach exploits the special cavity ansatz according to which the cavity ellipsoid is chosen to be conformal to the characteristic ellipsoid of the generalized permittivity tensor of the medium. Using a self-consistent procedure, analytical formulas for induced dipole and quadrupole moments and the macroscopic frozen-in polarization are obtained. The relashionship of the microscopic molecular characteristics (electric moments and polarizabilities) with macroscopic electret polarization, as well as with external macroscopic parameters (applied electric field and permittivity of the medium) is established.