title: An Ab Initio Description of the Excitonic Properties of LH2 and Their Temperature Dependence.
abstract: The spectroscopic properties of light-harvesting (LH) antennae in photosyntehtic organisms represent a fingerprint that is unique for each specific pigment-protein complex. Because of that, spectroscopic observations are generally combined with structural data from X-ray crystallography to obtain an indirect representation of the excitonic properties of the system. Here, an alternative strategy is presented which goes beyond this empirical approach and introduces an ab initio computational description of both structural and electronic properties and their dependence on the temperature. The strategy is applied to the peripheral light-harvesting antenna complex (LH2) present in purple bacteria. By comparing this model with the one based on the crystal structure, a detailed, molecular level explanation of the absorption and circular dichroism (CD) spectra and their temperature dependence is achieved. The agreement obtained with the experiments at both low and room temperature lays the groundwork for an atomistic understanding of the excitation dynamics in the LH2 system.
authors: Dipartimento di Chimica e Chimica Industriale, University of Pisa , Via G. Moruzzi 13, I-56124 Pisa, Italy.
authors: Lorenzo
authors: L
authors: Cupellini
authors: Dipartimento di Chimica e Chimica Industriale, University of Pisa , Via G. Moruzzi 13, I-56124 Pisa, Italy.
authors: Sandro
authors: S
authors: Jurinovich
authors: Dipartimento di Chimica e Chimica Industriale, University of Pisa , Via G. Moruzzi 13, I-56124 Pisa, Italy.
authors: Marco
authors: M
authors: Campetella
authors: Dipartimento di Chimica e Chimica Industriale, University of Pisa , Via G. Moruzzi 13, I-56124 Pisa, Italy.
authors: Stefano
authors: S
authors: Caprasecca
authors: Dipartimento di Chimica e Chimica Industriale, University of Pisa , Via G. Moruzzi 13, I-56124 Pisa, Italy.
authors: Ciro A
authors: CA
authors: Guido
authors: Life Sciences Biomolecular Sci, Joseph Black Building, University of Glasgow , Glasgow G12 8QQ, Scotland.
authors: Sharon M
authors: SM
authors: Kelly
authors: Glasgow Biomedical Research Centre, Institute of Molecular Cell and Systems Biology, University of Glasgow , 126 University Place, Glasgow G12 8TA, Scotland.
authors: Alastair T
authors: AT
authors: Gardiner
authors: Glasgow Biomedical Research Centre, Institute of Molecular Cell and Systems Biology, University of Glasgow , 126 University Place, Glasgow G12 8TA, Scotland.
authors: Richard
authors: R
authors: Cogdell
authors: Dipartimento di Chimica e Chimica Industriale, University of Pisa , Via G. Moruzzi 13, I-56124 Pisa, Italy.
authors: Benedetta
authors: B
authors: Mennucci
mesh_terms: D002942:Circular Dichroism; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000378:metabolism; D011789:Quantum Theory; D012241:Rhodopseudomonas / Q000737:chemistry; D013696:Temperature
chemical_list: D045342:Light-Harvesting Protein Complexes