Search results for "Atom model"
showing 6 items of 6 documents
Modelling the carbon Snoek peak in ferrite: Coupling molecular dynamics and kinetic Monte-Carlo simulations
2008
Abstract Molecular statics, molecular dynamics and kinetic Monte-Carlo are used to model the carbon Snoek peak in ferrite. Using an interatomic EAM potential for the Fe–C system, saddle point energies for the diffusion of carbon have been evaluated under uniaxial stress by molecular statics. These energies have been reintroduced in a kinetic Monte-Carlo scheme to predict the repartition of carbon atoms in different octahedral sites. This repartition leads to an anelastic deformation calculated by molecular dynamics, which causes internal friction (the Snoek peak) for cyclic stress. This approach leads to quantitative predictions of the internal friction, which are in good agreement with exp…
Heteroepitaxial growth of Co on W(110) investigated by scanning tunneling microscopy
2003
We investigated the growth of Co submonolayers on bcc W(110) by scanning tunneling microscopy. Due to the strong Co-W bonding, monolayers of Co grow in equilibrium pseudomorphically on W(110) until the monolayer is almost completed. When excess atoms are deposited atop the pseudomorphic monolayer, it transforms to a close-packed (cp) monolayer with misfit dislocation lines parallel to $[11\ifmmode\bar\else\textasciimacron\fi{}0]$ (Nishiyama-Wassermann orientation). The structure of the cp monolayer, as concluded from atomically resolved STM images, deviates from the rigid hard-sphere model of a cp (111) layer. Details of the structure are compared to a structure model previously proposed by…
(2S,3S)-2-(N,N-dibenzylamino)butane-1,3-diol refined using a multipolar atom model.
2008
The crystal structure of the title compound, C18H23NO2, was determined using the experimental library multipolar atom model. The refinement showed a significant improvement of crystallographic statistical indices when compared with a conventional spherical neutral atom refinement.
5-(3,4-Dimethoxybenzyl)-7-isopropyl-1,3,5-triazepane-2,6-dione acetonitrile solvate refined using a multipolar atom model
2010
International audience; The crystal structure of the title compound, C16H23N3O4·CH3CN, was refined using a multipolar atom model transferred from an experimental electron-density database. The refinement showed some improvement in crystallographic statistical indices compared with the independent atom model. The triazepane ring adopts a twist-boat conformation. In the crystal structure, the molecule forms intermolecular contacts with 14 different neighbours. There are two N-H...O and one C-H...O intermolecular hydrogen bond.
Trapping of hydrogen and helium at dislocations in tungsten: anab initiostudy
2017
Retention of plasma gas components such as hydrogen (H) isotopes and helium (He) is one of the limiting factors in selection of plasma facing materials for future thermonuclear fusion devices. Tungsten (W) is one of the promising candidates for such materials and was chosen for the divertor armor for International Thermonuclear Experimental Reactor (ITER) and the first wall material for the design of the demonstrational fusion power plant - DEMO. For the analytical estimation of accumulation of H/He components in tungsten, it is important to understand the relevant physical mechanisms of their trapping in the material and thoroughly parameterize them numerically. Experiments involving high …
4-Benzoyl-3,4-dihydro-2 H -1,4-benzoxazine-2-carbonitrile: refinement using a multipolar atom model
2009
The structural model for the title compound, C(16)H(12)N(2)O(2), was refined using a multipolar atom model transferred from an experimental electron-density database. The refinement showed some improvements of crystallographic statistical indices when compared with a conventional spherical neutral-atom refinement. The title compound adopts a half-chair conformation. The amide N atom lies almost in the plane defined by the three neighbouring C atoms. In the crystal structure, molecules are linked by weak intermolecular C-H...O and C-H...pi hydrogen bonds.