doi:10.1016/j.cplett.2005.03.012 
Copyright © 2005 Elsevier B.V. All rights reserved.
The influence of the structure of the radical cation dimer pair of aromatic molecules on the principal values of a g-tensor: DFT predictions
Alexander Petrenko
, 
, Kevin Redding and Lowell D. Kispert
Department of Chemistry, The University of Alabama, 206 Shelby Hall, 500 Campus Drive, Tuscaloosa, AL 35487-0336, USA
Received 27 January 2005;
revised 28 February 2005.
Available online 23 March 2005.
References and further reading may be available for this article. To view references and further reading you must
purchase this article.
Abstract
The density functional theory calculations were carried out to determine the influence of the structure of the radical cation dimer pair of model aromatic molecules on the principal values of a g-tensor. The calculated results for different model structures of (naphthalene)2 and (p-dimethylenebenzene)2 and individual model naphthalene and p-dimethylenebenzene molecules were analyzed by comparing results of calculations for different models. This comparison predicts an analogous effect for g-tensor principal values of 
special dimer pair radical cation in core Photosystem I and for g-tensor principal values of the 
special dimer pair triplet radical in core Photosystem I. The change in the g-tensor principal values in stacked structures of p-terphenyl cation radical was deduced from an extended model stacked multimer structure.
Fig. 1. The geometries of 
used in the g-tensor calculations (Dp is the p-dimethylenebenzene molecule). Face-to-face configurations PD1, PD2 and PD3 are shown displaced for clarity. The parallel-displaced structures of 
are characterized by a relative shift Δy of monomer units along the short axis of Dp: PD4 (Δy = 2.8 Å), PD5 (Δy = 1.4 Å). The interplane distances for all structures were taken equal 3.4 Å. The presented model structures were created using the modeling facilities of the Hyperchem 7 program package (Hypercube Inc., Gainesville, FL).
Fig. 2. The geometries of 
used in the g-tensor calculations (Np is the naphthalene molecule). Face-to-face configuration PD6, PD9 and PD10 are shown displaced for clarity. The parallel-displaced structures of 
are characterized by a relative shift Δx of monomer units along the long axis of Np, a relative shift Δy of monomer units along the short axis of Np and an interplane distance Δz: PD7 (Δx = 2.8 Å), PD8 (Δy = 2.8 Å) PD11 (Δx = 1.3 Å, Δy = 1.0 Å, Δz = 3.5 Å). The interplane distances for all structures were taken Δz = 3.4 Å (if not specified). The presented model structures were created using the modeling facilities of the Hyperchem 7 program package (Hypercube Inc., Gainesville, FL). The parallel-displaced structure PD11 has been identified in the ab initio calculations [15] as the global minimum structure of Np2.
Table 1.
The comparison of a calculated g-tensor anisotropy of model Dp+ and 
cation radicals (Dp–p-dimethylenebenzene)
For the numeration of structures see Fig. 1. If not specified, the basis set that was used is 6-31G(d).
a The basis set that was used is specified in parentheses.
Table 2.
The correlation between the downshift of the gYY component of a g-tensor (δgYY × 105) and the HOMO–HOMO electron transfer matrix element (β, eV) in different structures of 
a Electron transfer matrix elements estimated by method
[10].
b The value of
δgYY was calculated using the formula
.
Table 3.
Comparison of the calculated g-tensor anisotropies for the model Np+ and 
cation radicals (Np – naphthalene)
Experimental data for the Np+ cation radical obtained in [14]. The basis set that was used is 6-31G(d).
a The interplanar distance is specified in parentheses, if it is different than Δ
z = 3.4 Å.
Abstract
Purchase PDF (187 K)
E-mail Article
Add to my Quick Links
Cited By in Scopus (1)
= 2.020 and 
= 2.000 for this radical. The disulfide cation radical exhibited an evenly spaced septet of lines with 
Purchase PDF (621 K)
