M. Mrovec R. Gröger A. G. Bailey D. Nguyen-Manh C. Elsässer V. Vitek
We present a bond-order potential BOP for the bcc transition metal tungsten. The bond-order potentials are a real-space semiempirical scheme for the description of interatomic interactions based on the tight-binding approximation. In the hierarchy of atomic-scale-modeling methods the BOPs thus provide a direct bridge between electronic-structure an…
PublishedM. Yu. Lavrentiev R. Drautz D. Nguyen-Manh T. P. C. Klaver S. L. Dudarev
Iron-chromium alloys are characterized by a complex phase diagram, by the small negative enthalpy of mixing at low Cr concentrations in the bcc -phase of Fe, and by the inversion of the short-range order parameter. We present Monte Carlo simulations of the binary Fe-Cr alloy based on the cluster expansion approximation for the enthalpy of the syste…
PublishedM. J. Cawkwell D. Nguyen-Manh D. G. Pettifor V. Vitek
A tight-binding based bond-order potential BOP has been constructed for the fcc transition metal iridium that includes explicitly only d orbitals in the evaluation of the total energy.We show that hybridization between the nearly free electron sp band and the unsaturated covalently bonded d orbitals is important in determining the relative stabilit…
PublishedD. A. Murdick X. W. Zhou H. N. G. Wadley D. Nguyen-Manh R. Drautz D. G. Pettifor
An analytic, bond-order potential BOP is proposed and parametrized for the gallium arsenide system. The potential addresses primary and secondary bonding and the valence-dependent character of heteroatomic bonding, and it can be combined with an electron counting potential to address the distribution of electrons on the GaAs surface. The potential …
PublishedD. Nguyen-Manh A. P. Horsfield S. L. Dudarev
We present an investigation of systematic trends for the self-interstitial atom SIA defect behavior in body-centered cubic bcc transition metals using density-functional calculations. In all the nonmagnetic bcc metals the most stable SIA defect configuration has the 111 symmetry. Metals in group 5B of the periodic table V, Nb, Ta have significantly…
PublishedC. Lang D. J. H. Cockayne D. Nguyen-Manh
Atomistic simulations combining a Monte Carlo algorithm and molecular static relaxations were carried out to predict the alloying profile in pyramid and dome shaped Ge(Si)/Si(001) islands. The results show that the composition profile is dominated by the surface segregation of Ge and segregation of Si to the substrate island interface. Within the i…
PublishedRalf Drautz Dewey A. Murdick Duc Nguyen-Manh Xiaowang Zhou Haydn N. G. Wadley David G. Pettifor
An analytic interatomic bond-order potential BOP is derived that depends explicitly on the group number of the sp -valent element. This is achieved by generalizing the previously published BOP for group-IV elements by extrapolating from half-full occupancy using a simple envelope function for the upper bound of the bond order. This interatomic pote…
PublishedGuoqiang Liu D. Nguyen-Manh Bang-Gui Liu D. G. Pettifor
The tight-binding Stoner model of band magnetism is generalized to account for local charge neutrality by working within the tight-binding-bond s TBB d representation of the binding energy. We show that the analytic forces within this TBB Stoner model take a very simple form because neither the renormalization in the on-site energies due to local c…
PublishedD. A. Pankhurst Z. Yuan D. Nguyen-Manh M.-L. Abel G. Shao J. F. Watts D. G. Pettifor P. Tsakiropoulos
We have investigated the electronic structure of MoSi2, Mo5Si3, Mo3Si, and Mo(Si1−xAlx)2 alloys at a range of x values using a combination of valence-band x-ray photoelectron spectroscopy sVBXPSd and densityfunctional theory. We find good agreement between the experimental spectra and the calculated total densities of states. The observed differe…
Published