Jw. Van Der Horst et al., Calculation of excitonic properties of conjugated polymers using the Bethe-Salpeter equation, J CHEM PHYS, 114(15), 2001, pp. 6950-6957
The excitonic spectra of a number of conjugated polymers, polythiophene (PT
), polyphenylenevinylene (PPV), ladder-type poly-para-phenylene (LPPP), tra
ns-polyacetylene (PA), and polydiacetylene (PDA), are calculated by solving
the Bethe-Salpeter equation for the two-body Green function of the electro
n-hole pair. The only input to the calculation is the bulk dielectric const
ant. We find intermediate binding energies of 0.4-0.6 eV for the lowest opt
ical 1 B-1(u) exciton, obtaining good agreement with recent experiments for
each polymer individually. The agreement for the singlet-triplet splitting
s and the 1 B-1(u) polarizabilities is satisfactory. This also holds for th
e 1 B-1(u)-2 (1)A(g) splittings in PT, LPPP, and PPV. For PA and PDA we fin
d the 2 (1)A(g) exciton above the 1 B-1(u) exciton, in contrast with experi
ment; a possible explanation for this discrepancy is the absence of lattice
relaxation effects and double excitations in our calculations. (C) 2001 Am
erican Institute of Physics.