A density functional study of small Al

We report thermodynamic properties of small aluminium oxide clusters of mixed stoichiometric ratio AlxOy $(x,y=1{-}4)$. The rigid rotator-harmonic oscillator approximation is used to calculate the partition function as it is generally applied in thermodynamic studies of polyatomic molecules. The molecular data used to set up the partition functions were computed by density functional techniques employing the BP86 gradient corrected exchange correlation functional. Thereby, the results of three species viz. AlO4, Al4O2, and Al4O3 previously not reported in the literature are included in this study. Equilibrium geometric parameters, energies, selected harmonic vibrational wave numbers of energetically low–lying stationary points are presented along with corresponding absorption coefficients. The resulting thermodynamic functions of aluminium oxides are consistent with the JANAF thermochemical data compilation. These functions are used to determine the temperature dependent chemical equilibrium partial pressure distributions for different aluminium to oxygen ratios

Ab initio studies of stationary points of the Al

We report a theoretical ab initio investigation on energetically low-lying stationary points of the Al2O3 molecular system. The calculations were performed at the Hartree-Fock (HF) and second-order Møller-Plesset (MP2) frozen core level of approximation using the standard 6-31G(d) basis set. Several isomeric singlet as well as higher spin states of Al2O3 which lie close to each other within an energy range of about 8 eV (at MP2) are characterised. The lowest of these stationary points is in fact a triplet state of planar $\rm C_{2v}$ symmetry. It is by 0.08 eV (MP2) lower than the often discussed linear $\rm D_{\rm \infty h}$ singlet state. Atomisation energies for all species are quite large showing that the system is strongly bound. Energies, harmonic vibrational modes, and geometric parameters are compared with the results of earlier work by Solomonik and Sliznev [CITE], Nemukhin and Weinhold [CITE], Andrews et al. [CITE] and Desai et al. [CITE]. Based on our calculations we give a tentative assignment of some selected vibrational wave numbers and an interpretation of some features of the photoelectron spectrum

Services for numerical simulations and optimizations in grids

Numerical simulations are typically very compute intensive. A way to satisfy the arising demands for compute power is the employment of grid technology. But today, there exist only few tools, supporting the user in using grids for numerical simulations. Additionally, some basic problems of grid technology, are not solved with satisfaction. The goal of the project OptiNum-Grid was, to address these issues. We present a number of tools that were developed in the project. These are tools for parameter sweeps and optimizations in grids, for data security and automatic software installation, as well as for virtual environments in grids

Fab Mor03268 Triggers Absorption Shift of a Diagnostic Dye Via Packaging in a Solvent Shielded Fab Dimer Interface

Molecular interactions between near IR fluorescent probes and specific antibodies may be exploited to generate novel smart probes for diagnostic imaging. Using a new phage display technology, we developed such antibody Fab fragments with subnanomolar binding affinity for tetrasulfocyanine, a near IR in vivo imaging agent. Unexpectedly, some Fabs induced redshifts of the dye absorption peak of up to 44 nm. This is the largest shift reported for a biological system so far. Crystal structure determination and absorption spectroscopy in the crystal in combination with microcalorimetry and small angle X ray scattering in solution revealed that the redshift is triggered by formation of a Fab dimer, with tetrasulfocyanine being buried in a fully closed protein cavity within the dimer interface. The derived principle of shifting the absorption peak of a symmetric dye via packaging within a Fab dimer interface may be transferred to other diagnostic fluorophores, opening the way towards smart imaging probes that change their wavelength upon interaction with an antibod