An effective potential for Frenkel excitons

Abstract

EOP-TI – an approach for truly efficient calculations of both Förster and Dexter excitonic couplings.

Excitonic Configuration Interaction: Going Beyond the Frenkel Exciton Model

“…Hence, we refer to such a variational calculation of the full-system states as "Excitonic Configuration Interaction" (ECI) and to the APC-embedded products as "excitonic Slater determinants" (ESDs). Also, for the sake of brevity, we will refer to the GFT formulas (8), (9), and (10) with modifications (18) as the "ECI formulas". Not to be mistaken by the name, ESDs are not N el × N el SDs, but rather linear combinations of N el × N el SDs, because the APC-embedded site states are linear combinations of the site-specific SDs.…”

“…Note that, unlike in the FEM, we also in principle consider the couplings between two local excitations on the same site (those are part of H SS ). Both types of couplings are covered by the modified expression (9), although we note that this expression is more general and covers the couplings between any ESDs differing in one site state, regardless of their excitonic excitation ranks (GS, LE, DLE, Figure 2: (a) Schematic representation of the excitonic basis of ECIS, ECISD, and ECISDT bases on an example of a tri-chromophoric system with three site states (ground and two excited) supplied on each fragment. The chromophores are represented by hexagon, pentagon, and square, while the site states are denoted by colour (white: ground site state, purple and green: two excited site states).…”

“…Unfortunately, if the spectra of many different chromophores are overlapping, multichromophoric systems can acquire a very large density of states at low energies, which makes their electronic structure very challenging to describe. For the same reason, the ultrafast excitation energy transfer (EET) that takes place in such systems after a local photoexcitation 9 is very hard to simulate with excited-state molecular dynamics.…”

Perturbative Expansion of Nonorthogonal Product Approach for Charge Transfer States

“…The same extension can be used for the TrCAMM-based methods with the approximate two-electron integrals for Coulomb, exchange and CT components. 20 In our previous work, 13 we used the non-orthogonal product approach (NOPA) which is a method from the class of nonorthogonal configuration interaction (NOCI [21][22][23][24][25][26][27][28][29][30][31] ). These methods can either use CT-like basis functions constructed from the diabatic states [32][33][34] or CT wave functions of the ions calculated with the same method as for the neutral molecule as it is done in the current work.…”

“…For example, there are variants of the time-dependent density functional theory with local excitations and CT states or multistate modifications. , The transition density fragment interaction method can be improved by the transfer integrals (TDFI-TI , ). The same extension can be used for the TrCAMM-based methods with the approximate two-electron integrals for Coulomb, exchange, and CT components . In our previous work, we used the nonorthogonal product approach (NOPA) which is a method from the class of nonorthogonal configuration interaction (NOCI − ).…”