Mean-field theory of acentric order of chromophores with displaced dipoles

A mean-field model of acentric order of dipolar chromophores in polymeric e lectro-optic materials is developed by extension of our earlier results [Y. V. Pereverzev, O.V. Prezhdo, Phys. Rev. E 62 (2000) 8324] to allow for posi tion and orientation flexibility of chromophore dipoles with respect of the molecular frame. The extended model quantitatively reproduces the experime ntal data for two sample chromophore systems. The model indicates that the disappearance of the acentric order and the related turnover and decay of t he electro-optic coefficient are associated with a second-order phase trans ition in the dipolar system from para- to antiferroelectric state. (C) 2001 Elsevier Science B.V. All rights reserved.