Physical Chemistry Chemical Physics

doi: 10.1039/c0cp90037kpmid: N/A

doi: 10.1039/c0cp90038apmid: N/A

doi: 10.1039/c0cp90039gpmid: N/A

de Jong, Wibe A.; Bylaska, Eric; Govind, Niranjan; Janssen, Curtis L.; Kowalski, Karol; Müller, Thomas; Nielsen, Ida M. B.; van Dam, Hubertus J. J.; Veryazov, Valera; Lindh, Roland

doi: 10.1039/c002859bpmid: 20532308

Christensen, Morten; Haldrup, Kristoffer; Kjær, Kasper S.; Cammarata, Marco; Wulff, Michael; Bechgaard, Klaus; Weihe, Høgni; Harrit, Niels H.; Nielsen, Martin M.

doi: 10.1039/c002070bpmid: 20467685

Parida, Prakash; Kundu, Anasuya; Pati, Swapan K.

doi: 10.1039/c004653cpmid: 20490413

Using density functional theory, we have investigated the structural, electronic and magnetic properties of infinitely periodic organometallic vanadium–anthracene ([V2Ant]∞) and [V4(BNAnt)2]∞ (where BNAnt is B–N analogue of anthracene) for their possible application in spintronics. From our calculations, we find that one-dimensional [V2Ant]∞ and [V4(BNAnt)2]∞ wires exhibit robust ferromagnetic half-metallic and metallic behavior, respectively. The finite sized V6Ant2 and V6(BNAnt)2 clusters are also found to exhibit efficient spin filter properties when coupled to graphene electrodes on either side.

Pérez-Hernández, Natalia; Luong, Trung Quan; Pérez, Cirilo; Martín, Julio D.; Havenith, Martina

doi: 10.1039/c000985gpmid: 20461236

We measured the FIR (Far Infrared) absorbance of a series of organic hydrated sub-nanopores (i.e. pores of the size of several Å) containing confined water. Our results show that the FIR frequency region between 400 and 570 cm−1 is sensitive to the differences in water mobility. The absorbance of these compounds was significantly higher than that of chemically similar anhydrous or non-porous hydrated compounds in the same region. Moreover, changes in the water dynamics inside the hydrated pores were found and characterized by their temperature dependent studies in the range from −5 to 20 °C. Upon increasing the temperature, water confined in narrow pores shows a small increase in FIR absorbance, while less confined water molecules inside larger pores exhibit a higher increase in absorbance, resembling more what has been observed for bulk water.

Wang, Chao; Wang, Guofeng; van der Vliet, Dennis; Chang, Kee-Chul; Markovic, Nenad M.; Stamenkovic, Vojislav R.

doi: 10.1039/c000822bpmid: 20526494

Monodisperse Pt3Co nanoparticles have been synthesized with size control via an organic solvothermal approach. The obtained nanoparticles were incorporated into a carbon matrix and applied as electrocatalysts for the oxygen reduction reaction to investigate the effects of particle size and pretreatment on their catalytic performance. It has been found that the optimal conditions for maximum mass activity were with particles of ∼4.5 nm and a mild annealing temperature of about 500 °C. While the particle size effect can be correlated to the average surface coordination number, Monte Carlo simulations have been introduced to depict the nanoparticle structure and segregation profile, which revealed that the annealing temperature has a direct influence on the particle surface relaxation, segregation and adsorption/catalytic properties. The obtained fundamental understanding of activity enhancement in Pt-bimetallic alloy catalysts could be utilized to guide the development of advanced nanomaterials for catalytic applications.

Huenerbein, Robert; Schirmer, Birgitta; Moellmann, Jonas; Grimme, Stefan

doi: 10.1039/c003951apmid: 20461239

A benchmark set of 24 isomerization reactions of large organic molecules (consisting of 24 to 81 atoms) is presented (termed ISOL). The molecules are much larger than what is typically considered in thermochemical tests. To obtain reference isomerization energies, complete basis set (CBS) extrapolations at the (SCS)-MP2 level have been computed that are augmented by perturbative third-order corrections (SCS-MP3 and MP2.5 methods). Based on these carefully examined reference data, a diverse set of common density functionals varying from GGA to double-hybrid functional level with and without dispersion correction (DFT-D) is tested. Double-hybrid and the PBE0 hybrid functionals are found to be the methods of choice for the type of main group thermochemistry examined here. For all isomerizations with an average reaction energy of 22.7 kcal mol−1 (in a range between 0.5 and 74.5 kcal mol−1), PBE0-D, B2PLYP-D and B2GP-PLYP-D yield mean absolute deviations of 2.5, 4.1 and 2.9 kcal mol−1. Most importantly it is found that the use of a dispersion correction is essential if such large molecules are considered. For all DFT methods the MAD is lowered very significantly by 1.4–5.0 kcal mol−1 when DFT-D is used. Intramolecular (mainly medium-range) London dispersion interactions account in some cases for more than 50% (41 kcal mol−1) of the isomerization energy even though the size of the systems remains unchanged. This study also demonstrates for the first time clearly that typical DFT errors are larger than expected (about 5 kcal mol−1) and that chemical accuracy (about 1 kcal mol−1) even for these electronically well-behaved molecules is currently not reached by DFT. We propose this new test set as a difficult challenge for electronic structure methods that claim to be routinely applicable to large molecules. We also suggest to use a distance range resolved dispersion energy as a diagnostic for problematic cases in DFT.

Ohoyama, H.; Kasai, T.

doi: 10.1039/c000460jpmid: 20458424

Multi-dimensional steric effect for the XeI* (B) formation in the oriented Xe* (3P2, MJ = 2) + oriented CH3I reaction has been observed as a function of the mutual configuration between the molecular orientation and the atomic alignment in the collision frame. The molecular steric opacity function has been determined as a function of the atomic orbital alignment. The large molecular orientation dependence (i.e., the largest reactivity at the I-end and the large difference in the reaction probability between the I-end and the CH3-end) and the large molecular alignment dependence (the poor reactivity at the sideway) is recognized for each atomic orbital alignment. In addition, a clear correlation between the molecular orientation and the atomic orbital alignment is recognized (i.e., the LZ′ = 0 atomic orbital alignment is favorable for the molecular axis direction, while the |LZ′| = 1 atomic orbital alignment is favorable for the sideway direction).