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Schlogl R.,Fritz Haber Institute of the Max Planck Society | Schlogl R.,Max Planck Institute for Chemical Energy Conversion
Angewandte Chemie - International Edition | Year: 2015

A heterogeneous catalyst is a functional material that continually creates active sites with its reactants under reaction conditions. These sites change the rates of chemical reactions of the reactants localized on them without changing the thermodynamic equilibrium between the materials. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.

Sharma S.,Princeton University | Sivalingam K.,Max Planck Institute for Chemical Energy Conversion | Neese F.,Max Planck Institute for Chemical Energy Conversion | Chan G.K.-L.,Princeton University
Nature Chemistry | Year: 2014

Iron-sulfur clusters are a universal biological motif. They carry out electron transfer, redox chemistry and even oxygen sensing, in diverse processes including nitrogen fixation, respiration and photosynthesis. Their low-lying electronic states are key to their remarkable reactivity, but they cannot be directly observed. Here, we present the first ever quantum calculation of the electronic levels of [2Fe-2S] and [4Fe-4S] clusters free from any model assumptions. Our results highlight the limitations of long-standing models of their electronic structure. In particular, we demonstrate that the widely used Heisenberg double exchange model underestimates the number of states by one to two orders of magnitude, which can conclusively be traced to the absence of Fe dd excitations, thought to be important in these clusters. Furthermore, the electronic energy levels of even the same spin are dense on the scale of vibrational fluctuations and this provides a natural explanation for the ubiquity of these clusters in catalysis in nature. © 2014 Macmillan Publishers Limited. All rights reserved.

Sparta M.,Max Planck Institute for Chemical Energy Conversion | Neese F.,Max Planck Institute for Chemical Energy Conversion
Chemical Society Reviews | Year: 2014

The scope of this review is to provide a brief overview of the chemical applications carried out by local pair natural orbital coupled-electron pair and coupled-cluster methods. Benchmark tests reveal that these methods reproduce, with excellent accuracy, their canonical counterparts. At the same time, the speed up achieved by exploiting the locality of the electron correlation permits us to tackle chemical systems that, due to their size, would normally only be addressable with density functional theory. This review covers a broad variety of the chemical applications e.g. simulation of transition metal catalyzed reactions, estimation of weak interactions, and calculation of lattice properties in molecular crystals. This demonstrates that modern implementations of wavefunction-based correlated methods are playing an increasingly important role in applied computational chemistry. This journal is © the Partner Organisations 2014.

Pantazis D.A.,Max Planck Institute for Chemical Energy Conversion | Neese F.,Max Planck Institute for Chemical Energy Conversion
Wiley Interdisciplinary Reviews: Computational Molecular Science | Year: 2014

All-electron (AE) calculations for chemical systems containing atoms of elements beyond krypton are becoming increasingly accessible and common in many fields of computational molecular science. The type, the size, and the internal construction of AE basis sets for heavy elements depend critically on the level of quantum chemical theory and, most importantly, on the way relativistic effects are treated. For this reason, general-purpose basis sets for heavy elements are rare; instead, different AE basis sets have been developed that are adapted to the requirements and peculiarities of each (approximate) relativistic treatment. Ranging from fully relativistic four-component approaches to more popular scalar relativistic approximations, today there exist complete families of AE basis sets that can cover most research needs and can be employed in diverse applications for the proper description of various molecular and atomic properties including electronic structure, chemical reactivity, and a wide range of spectroscopic parameters. © 2013 John Wiley & Sons, Ltd.

Schapiro I.,Max Planck Institute for Chemical Energy Conversion | Ruhman S.,Hebrew University of Jerusalem
Biochimica et Biophysica Acta - Bioenergetics | Year: 2014

Light induced isomerization of the retinal chromophore activates biological function in all retinal protein (RP) driving processes such as ion-pumping, vertebrate vision and phototaxis in organisms as primitive as archea, or as complex as mammals. This process and its consecutive reactions have been the focus of experimental and theoretical research for decades. The aim of this review is to demonstrate how the experimental and theoretical research efforts can now be combined to reach a more comprehensive understanding of the excited state process on the molecular level. Using the Anabaena Sensory Rhodopsin as an example we will show how contemporary time-resolved spectroscopy and recently implemented excited state QM/MM methods consistently describe photochemistry in retinal proteins. This article is part of a Special Issue entitled: Retinal Proteins - You can teach an old dog new tricks. © 2013 Published by Elsevier B.V.

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