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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. February 2006, Volume 5, Number 2, 89-101 |
Structural and Spectroscopic Studies of Chlorophyll c3 using DFT and TD-DFT Methods
Mama Nsangou, Nejm-Eddine Jaïdane, and Zohra Ben Lakhdar
Internet Electron. J. Mol. Des. 2006, 5, 89-101
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Abstract:
In the present paper we use quantum chemical methods to optimize
the molecular structure of the chlorophyll c3 (Chl.c3) and
determine its molecular parameters and charges. Two theoretical
methods have been used in this study, namely modified neglect of
differential overlap with d-orbitals on some atoms (MNDO-d) and
the density functional theory (DFT). In the DFT calculations we
have used the Becke three parameters (B3) exchange functional,
combined with the Lee-Yang-Parr (LYP) correlation functional.
The time dependent density functional theory (TD-DFT) was used
In the calculation of excited states. The molecular structure of the
Chl.c3 and the Chl.c3 dimer has been successfully optimized and
shows that the Chl.c3 macrocycle is non planar. In the monomer
the Mg atom, coordinated to four nitrogen atoms, is neither located
at the center nor in the porphyrin plane. Furthermore, TD-DFT
calculations have successfully predicted the UV/visible absorption
spectra of the Chl.c3. The molecular structure and spectra
predicted may help in an extensive experimental study of the
ground- and excited-states of the Chl.c3 molecular system.
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