A general ansatz for constructing quasi-diabatic states in electronically excited aggregated systems.
We present a general method for analyzing the character of singly excited states in terms of charge transfer (CT) and locally excited (LE) configurations. The analysis is formulated for configuration interaction singles (CIS) singly excited wave functions of aggregate systems. It also approximately works for the second-order approximate coupled cluster singles and doubles and the second-order algebraic-diagrammatic construction methods [CC2 and ADC(2)]. The analysis method not only generates a weight of each character for an excited state, but also allows to define the related quasi-diabatic states and corresponding coupling matrix elements. In the character analysis approach, we divide the target system into domains and use a modified Pipek-Mezey algorithm to localize the canonical MOs on each domain, respectively. The CIS wavefunction is then transformed into the localized basis, which allows us to partition the wavefunction into LE configurations within domains and CT configuration between pairs of different domains. Quasi-diabatic states are then obtained by mixing excited states subject to the condition of maximizing the weight of one single LE or CT configuration (localization in configuration space). Different aims of such a procedure are discussed, either the construction of pure LE and CT states for analysis purposes (by including a large number of excited states) or the construction of effective models for dynamics calculations (by including a restricted number of excited states). Applications are given to LE/CT mixing in π-stacked systems, charge-recombination matrix elements in a hetero-dimer, and excitonic couplings in multi-chromophoric systems.
Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
Wenlan
W
Liu
InnovationLab GmbH, Speyerer St. 4, D-69115 Heidelberg, Germany.
Bernd
B
Lunkenheimer
Institute of Physical and Theoretical Chemistry, University of Würzburg, Emil-Fischer-St. 42, D-97074 Würzburg, Germany.
Volker
V
Settels
Institute of Physical and Theoretical Chemistry, University of Würzburg, Emil-Fischer-St. 42, D-97074 Würzburg, Germany.
Bernd
B
Engels
Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, D-72076 Tübingen, Germany.
Reinhold F
RF
Fink
Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
Andreas
A
Köhn
D000465:Algorithms; D011789:Quantum Theory