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Rozanska X.,Materials Design S.a.r.l. | Ungerer P.,Materials Design S.a.r.l. | Leblanc B.,Materials Design S.a.r.l. | Saxe P.,Materials Design Inc. | Wimmer E.,Materials Design S.a.r.l.
Oil and Gas Science and Technology | Year: 2015

This work demonstrates the systematic prediction of thermodynamic properties for batches of thousands of molecules using automated procedures. This is accomplished with newly developed tools and functions within the Material Exploration and Design Analysis (MedeAβ) software environment, which handles the automatic execution of sequences of tasks for large numbers of molecules including the creation of 3D molecular models from 1D representations, systematic exploration of possible conformers for each molecule, the creation and submission of computational tasks for property calculations on parallel computers, and the post-processing for comparison with available experimental properties. After the description of the different MedeAβ functionalities and methods that make it easy to perform such large number of computations, we illustrate the strength and power of the approach with selected examples from molecular mechanics and quantum chemical simulations. Specifically, comparisons of thermochemical data with quantum-based heat capacities and standard energies of formation have been obtained for more than 2 000 compounds, yielding average deviations with experiments of less than 4% with the Design Institute for Physical PRoperties (DIPPR) database. The automatic calculation of the density of molecular fluids is demonstrated for 192 systems. The relaxation to minimum-energy structures and the calculation of vibrational frequencies of 5 869 molecules are evaluated automatically using a semi-empirical quantum mechanical approach with a success rate of 99.9%. The present approach is scalable to large number of molecules, thus opening exciting possibilities with the advent of exascale computing. © X. Rozanska et al. Source

Kwon J.,University of Texas at Dallas | Dai M.,University of Texas at Dallas | Halls M.D.,Materials Design Inc. | Chabal Y.J.,University of Texas at Dallas
Applied Physics Letters | Year: 2010

We demonstrate that interfacial SiO2, usually formed during high- κ oxide growth on silicon using ozone (O3), is suppressed during Al2 O3 atomic layer deposition (ALD) by decreasing the O3 flow rate. First-principles calculations indicate that oxygen introduced by the first low-dose O3 exposure is inserted into the surface nucleation layer rather than the Si lattice. Subsequent Al2 O3 deposition further passivates the surface against substrate oxidation. Aluminum methoxy [-Al (OCH3)2] and surface Al-O-Al linkages formed after O3 pulses are suggested as the reaction sites for trimethylaluminum during ALD of Al2 O3. © 2010 American Institute of Physics. Source

Kwon J.,University of Texas at Dallas | Saly M.,SAFC Hitech | Halls M.D.,Materials Design Inc. | Kanjolia R.K.,SAFC Hitech | Chabal Y.J.,University of Texas at Dallas
Chemistry of Materials | Year: 2012

Tertbutylallylcobalttricarbonyl ( tBu-AllylCo(CO) 3) is shown to have strong substrate selectivity during atomic layer deposition of metallic cobalt. The interaction of tBu-AllylCo(CO) 3 with SiO 2 surfaces, where hydroxyl groups would normally provide more active reaction sites for nucleation during typical ALD processes, is thermodynamically disfavored, resulting in no chemical reaction on the surface at a deposition temperature of 140 °C. On the other hand, the precursor reacts strongly with H-terminated Si surfaces (H/Si), depositing ∼1 ML of cobalt after the first pulse by forming Si-Co metallic bonds. This remarkable substrate selectivity of tBu-AllylCo(CO) 3 is due to an ALD nucleation reaction process paralleling a catalytic hydrogenation, which requires a coreactant that acts as a hydrogen donor rather than a source of bare protons. The chemical specificity demonstrated in this work suggests a new paradigm for developing selective ALD precursors. Namely, selectivity can be achieved by tailoring the ligands in the coordination sphere to obtain structural analogues to reaction intermediates for catalytic transformations that exhibit the desired chemical discrimination. © 2012 American Chemical Society. Source

Wimmer E.,Materials Design Inc. | Wimmer E.,Materials Design S.a.r.l. | Celasco E.,CNR Institute of Neuroscience | Celasco E.,University of Genoa | And 19 more authors.
Surface Science | Year: 2016

This comment clarifies two issues related to the (001) surface reconstructions of cubic SiC, namely: (i) The failure of the bridge-bond model for H atoms interacting with the 3C-SiC(001) 3 × 2 reconstruction to explain all the experimental data based on different techniques, while a recent model has reconciled theory and experimental results. This model has not been discussed or even mentioned in the review by Pollmann et al.; and (ii) In their review, two models of the Si-terminated c(4 × 2) 3C-SiC(001) surface reconstruction are presented as equally probable. This is clearly not the case and the reasons are explained in this comment. © 2015 Elsevier B.V. All rights reserved. Source

Christensen M.,Materials Design Inc. | Angeliu T.M.,Knolls Atomic Power Laboratory | Ballard J.D.,Knolls Atomic Power Laboratory | Vollmer J.,Knolls Atomic Power Laboratory | And 2 more authors.
Journal of Nuclear Materials | Year: 2010

Effects of twenty impurity and alloy elements on the strength of a Zr(0 0 0 1)/Zr(0 0 0 1) ∑7 twist grain boundary were studied using a first-principles density functional approach. A ranking in the order of most weakening to most strengthening was: Cs, I, He, Te, Sb, Li, O, Sn, Cd, H, Si, C, N, B, U, Ni, Hf, Nb, Cr, and Fe. Segregation energies for these elements to the grain boundary and the Zr(0 0 0 1) surface were also calculated. Calculations showed that the weakening grain boundary elements He, I, and Cs have a strong driving force for segregation to the grain boundary from bulk Zr. Zircaloy cladding failures (pellet-clad interactions) in commercial fuel systems and separate effects test results provide context for these computational results. © 2010 Elsevier B.V. All rights reserved. Source

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