Transition density cube method

Czader A, Bittner ER (2008) Calculations of the exciton coupling elements between DNA bases using the transition density cube method. J Chem Phys 128 035101... 

Krueger, B. P., G. D. Scholes, and G. R. Fleming. 1998. Calculation of couplings and energy-transfer pathways between the pigments of LH2 by the ab initio transition density cube method. J. Phys. Chem. B 102 5378-5386. 

A more rigorous approach, however, is to directly compute the interaction between the transition densities. This was first done numerically by discretizing the transition densities into finite volume elements of a 3D grid in the transition density cube (TDC) method [84]... 

To execute Eq. (3) numerically, we have used ab initio quantum chemical methods to calculate transition density cubes (TDCs) for the donor and acceptor from CTsingles or time-dependent density functional theory wavefunctions. A TDC is simply a discretized transition density. 

However, because the shape of the TD is well-calculated, it is possible to scale uniformly the TDC in such a way that Eq. (8) gives the experimental result for the transition dipole moment p P. We do this by multiplying each element in the cube by p P/(or equivalently post-processing the calculated coupling). This method does not work for forbidden transitions, of course. If TDs are calculated using time-dependent density functional theory or semiempirical methods like ESfDO [82], no scaling is necessary [83]. 

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