Comparison of the Coulomb and non-orthogonal approaches to the construction of the exciton Hamiltonian

On the role of dynamic electron correlation in non-orthogonal configuration interaction with fragments

“…However, the increasing computer power and the fact that NOCI is very well suited for parallelization 32 has caused a revival of the computational schemes in which the orthogonality restrictions have been removed. 33–48…”

Perturbative expansion of non-orthogonal product approach for charge-transfer states

“…At a close distance the overlap and exchange contributions might be significant. 12 These contributions can be calculated using the transition density fragment interaction method (TDFI 13 ). In this case, a significant contribution of charge transfer (CT) to the excited states can also take place.…”

“…In this case, a significant contribution of charge transfer (CT) to the excited states can also take place. 12,14 To take this factor into account, the CT states are to be added in the excitonic Hamiltonian basis. Such extended Hamiltonian can be used not only for the excited states properties and dynamics description, but also for the electron transfer modeling in bacterial and plant photosynthetic reaction centers, for example.…”

“…16,17 Transition density fragment interaction method 13 can be improved by the transfer integrals (TDFI-TI 14 ). In our previous work 12 we used the non-orthogonal product approach (NOPA) which is a method from the class of non-orthogonal configuration interaction (NOCI [18][19][20][21][22][23][24][25][26] ).…”

An effective potential for Frenkel excitons

“…Such an approach is quite reliable in the weak-coupling limit 17 and can be extended to account for intermolecular charge transfer states. [18][19][20][21] To accurately account for short-range effects, fragment density approaches (FDAs) were developed, 13,22,23 in which the analysis of the Hamiltonian is performed in the eigenstate basis for the initial and final EET states of interest. In particular, the fragment excitation difference (FED) approach, 13 which is a generalization of the energy splitting in dimer (ESD) method 24 for nonsymmetric systems, provides reasonably accurate values of EET at all physically meaningful intermolecular distances.…”