6,026 research outputs found
pi-Xi correlations in d+Au and Au+Au collisions at STAR
Qualitative comparison of source sizes from pi-Xi correlations analyses in
d+Au and Au+Au collisions at sqrt(s_NN)=200G GeV and sqrt(s_NN)=62 GeV is
presented. For the most central Au+Au collisions at sqrt(s_NN)=200 GeV we
report first quantitative results concerning size of the pi-Xi source and
relative shift of the average emission points between pi and Xi showing that
the homogeneity region of Xi source is smaller then that of pion and
significantly shifted in the transverse direction.Comment: prepared for the poster-session proceedings of the 19th International
Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (QM2006
Hybrid quantum/classical study of hydrogen-decorated screw dislocations in tungsten : ultrafast pipe diffusion, core reconstruction, and effects on glide mechanism
The interaction of hydrogen (H) with dislocations in tungsten (W) must be understood in order to model the mechanical response of future plasma-facing materials for fusion applications. Here, hybrid quantum mechanics/molecular mechanics (QM/MM) simulations are employed to study the ⟨111⟩ screw dislocation glide in W in the presence of H, using the virtual work principle to obtain energy barriers for dislocation glide, H segregation, and pipe diffusion. We provide a convincing validation of the QM/MM approach against full DFT energy-based methods. This is possible because the compact core and relatively weak elastic fields of ⟨111⟩ screw dislocations allow them to be contained in periodic DFT supercells. We also show that H segregation stabilizes the split-core structure while leaving the Peierls barrier almost unchanged. Furthermore, we find an energy barrier of less than 0.05 eV for pipe diffusion of H along dislocation cores. Our quantum-accurate calculations provide important reference data for the construction of larger-scale material models
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