First-principles study of spontaneous polarization in tetrathiafulvalene-p-chloranil (TTF-CA)

We have performed first-principles calculations on the organic compound tetrathiafulvalene-p-chloranil (TTF-CA TTF= C(6)H(4)S(4) CA = C(6)Cl(4)O(2)) in order to evaluate its spontaneous polarization The obtained value on the experimental structure is 0 10C/m(2) while It is 0 12 C/m(2) on the structure with the computationally optimized atomic positions These values are significantly larger than the existing experimental value of 0 4 x 10(2) C/m(2) [E Collet PhD Thesis University of Rennes 1 1999] The origin of the calculated large spontaneous polarization is discussed (C) 2009 Elsevier B V All rights reserved