Coulomb interactions and linear, nonlinear, and triplet absorption in poly(para-phenylenevinylene)

Photophysics of a poly(phenylenevinylene) with alternatingmeta-phenylene andpara-phenylene rings

“…23 Others believe that the effects of CCS breaking alone are weak and have little effect on the optical properties of the material. 8,[26][27][28] Within this context, the strength of band II is closely related to the effective conjugation length of the polymer. It is therefore intriguing that band II is especially strong in 1,3-PPV, where the incorporation of metaphenylene rings alters the symmetry and restricts conjugation.…”

“…The absorption spectrum of PPV consists of bands at 3.0, 3.8, 4.8, and 6 eV. 8,[23][24][25][26] Substituted derivatives of PPV exhibit the same structure, although the energy and relative strength of each band depends upon the substituent. 1,3-PPV shows two significant differences from other substituted PPV derivatives: the absorption band at 3.8 eV ͑band II͒ is unusually strong and an additional band at 5.5 eV can be seen.…”

A Fortran 90 Hartree–Fock program for one-dimensional periodic π-conjugated systems using Pariser–Parr–Pople model

“…Therefore, in the absence of any reliable experimental data on the GNR band gaps, we have decided to use the original screened parameters of Chandross and Mazumdar(author?) [52], with U = 8.0 eV and κ i,j = 2.0 (i = j) and κ i,i = 1.…”

“…Thus, after trying a number of Coulomb parameters, and in the absence of any experimental data on the band gaps of GNRs, we have decided it is best to use the original screened parameters of Chandross and Mazumdar(author?) [52], with U = 8.0 eV and κ i,j = 2.0 (i = j) and κ i,i = 1 for all the GNRs. But, we would like to emphasize that the user has the freedom to choose a different set of Coulomb parameters as per the requirements, and, we encourage such experimentation.…”

“…) [10] to obtain a set of "modified screened Coulomb parameters," with U = 6.0 eV and κ i,j = 2.0 (i = j) and κ i,i = 1, which are slightly different from the screened parameters reported initially by Chandross and Mazumdar(author?) [52], with U = 8.0 eV and κ i,j = 2.0 (i = j) and κ i,i = 1, aimed at describing the optical properties of phenyl-based polymers within the P-P-P model. The modified screened parameters provided good agreement between our HF band gaps, and those obtained by the GW method for a few AGNRs, however, for ZGNRs the agreement was not good(author?)…”