Symmetry-adapted density matrix renormalization group calculations of the primary excited states of poly(para-phenylene vinylene)

Abstract

The Pariser-Parr-Pople model of pi-conjugated electrons is solved by a three-block, symmetry-adapted density matrix renormalization group (DMRG) method for the light emitting polymer, poly(para-phenylene vinylene). The energies of the primary excited states are calculated. There is excellent agreement between theory and experiment when solid state screening is incorporated into the model parameters, enabling us to make an identification of the origin of the key spectroscopic features. Appendices describe important technical aspects of the three-block DMRG approach: Local Hilbert space efficiency and its relation to the matrix product formulation of the DMRG; an efficient computational procedure for constructing symmetry-adapted states for DMRG calculations; and correct superblock state targeting to ensure good convergence of the method.

Spin-orbit interactions between interchain excitations in conjugated polymers

“…In our DMRG algorithm we employ the sparse symmetry operator techniques for computing symmetry adapted eigenstates described in Ref. 41. This approach allows us to target eigenstates with specific spin-flip, particle-hole, and reflection ͑short and long axis in the case of coupled chains͒ symmetries by expressing the DMRG superblock symmetry operators as tensor products of operators from the individual blocks that make up the superblock ͑in the case of the present model, a system block, a reflected system block, and two added repeat units in the middle͒.…”

“…The derivation of this result, presented in the appendix of Ref. 41, assumed that all superblock target states making up the Gibbs state projection operator that is partially traced to form the reduced ͑augmented block͒ density matrix have total S s z =0 ͑these can be singlets or S s z = 0 branches of triplet excitations͒. It was mentioned that it is possible to generalize the Gibbs states to include target states with nonzero superblock z spin.…”

Singlet Triplet-Pair Production and Possible Singlet-Fission in Carotenoids

“…Convergence of the closely related Pariser-Parr-Pople-Peierls model has been extensively studied. [34][35][36][37] In general, in t-DMRG the number of states required to represent a time-evolving state vector accurately is given by…”

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

“…[28,29,30,31,32,33,34,35,36,37,38,39,40], along with numerous other groups(author?) [1,2,3,41,42,43,44,45,46], have used the P-P-P model to study the electronic structure and optical properties of conjugated molecules and oligomers. For finite π-conjugated systems, in our group, we have developed a general-purpose HF program employing the P-P-P model, which is available to anyone for scientific work(author?)…”