@article{KroenerGoetze2012,
  author    = {Kr{\"o}ner, Dominik and G{\"o}tze, Jan Philipp},
  title     = {Modeling of a violaxanthin-chlorophyll b chromophore pair in its LHCII environment using CAM-B3LYP},
  series = {Journal of photochemistry and photobiology : B, Biology},
  volume    = {109},
  journal   = {Journal of photochemistry and photobiology : B, Biology},
  number    = {2},
  publisher = {Elsevier},
  address   = {Lausanne},
  issn      = {1011-1344},
  doi       = {10.1016/j.jphotobiol.2011.12.007},
  pages     = {12 -- 19},
  year      = {2012},
  abstract  = {Collecting energy for photosystem II is facilitated by several pigments, xanthophylls and chlorophylls, embedded in the light harvesting complex II (LHCII). One xanthophyll, violaxanthin (Vio), is loosely bound at a site close to a chlorophyll b (Chl). No final answer has yet been found for the role of this specific xanthophyll. We study the electronic structure of Vio in the presence of Chl and under the influence of the LHCII environment, represented by a point charge field (PCF). We compare the capability of the long range corrected density functional theory (DFT) functional CAM-B3LYP to B3LYP for the modeling of the UV/vis spectrum of the Vio + Chl pair. CAM-B3LYP was reported to allow for a very realistic reproduction of bond length alternation of linear polyenes, which has considerable impact on the carotenoid structure and spectrum. To account for the influence of the LHCII environment, the chromophore geometries are optimized using an ONIOM(DFT/6-31G(d):PM6) scheme. Our calculations show that the energies of the locally excited states are almost unaffected by the presence of the partner chromophore or the PCF. There are, however, indications for excitonic coupling of the Chl Soret band and Vio. We propose that Vio may accept energy from blue-light excited Chl.},
  language  = {en}
}
@article{GoetzeSaalfrank2012,
  author    = {G{\"o}tze, Jan Philipp and Saalfrank, Peter},
  title     = {Quantum chemical modeling of the kinetic isotope effect of the carboxylation step in RuBisCO},
  series = {Journal of molecular modeling},
  volume    = {18},
  journal   = {Journal of molecular modeling},
  number    = {5},
  publisher = {Springer},
  address   = {New York},
  issn      = {1610-2940},
  doi       = {10.1007/s00894-011-1207-0},
  pages     = {1877 -- 1883},
  year      = {2012},
  abstract  = {Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), the most important enzyme for the assimilation of carbon into biomass, features a well-known isotope effect with regards to the CO2 carbon atom. This kinetic isotope effect alpha = k (12)/k (13) for the carboxylation step of the RuBisCO reaction sequence, and its microscopic origin, was investigated with the help of cluster models and quantum chemical methods [B3LYP/6-31G(d,p)]. We use a recently proposed model for the RuBisCO active site, in which a water molecule remains close to the reaction center during carboxylation of ribulose-1,5-bisphosphate [B. Kannappan, J.E. Gready, J. Am. Chem. Soc. 130 (2008), 15063]. Alternative active-site models and/or computational approaches were also tested. An isotope effect alpha for carboxylation is found, which is reasonably close to the one measured for the overall reaction, and which originates from a simple frequency shift of the bending vibration of (CO2)-C-12 compared to (CO2)-C-13. The latter is the dominant mode for the product formation at the transition state.},
  language  = {en}
}