نتایج جستجو برای: hexagonal close packed

تعداد نتایج: 214654  

Journal: :Physical review letters 2012
Andreea Panaitescu K Anki Reddy Arshad Kudrolli

We investigate the nucleation of ordered phases, their symmetries, and distributions in dense frictional hard sphere packings as a function of particle volume fraction ϕ, by imposing cyclic shear and constant applied pressure conditions. We show, with internal imaging, that the nucleating crystallites in the bulk consist of 10-60 spheres with hexagonal close packed (hcp) order and nonspherical ...

Journal: :The Journal of chemical physics 2006
S Mehta G D Price D Alfè

The finite temperature density functional theory and quasiharmonic lattice dynamics have been used to compute numerous thermodynamic properties of hexagonal close packed magnesium using both the local density approximation (LDA) and the generalized gradient approximation (GGA) for the exchange-correlation potential. Generally, it is found that there exist only minor differences between the LDA ...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2001
D L Blair N W Mueggenburg A H Marshall H M Jaeger S R Nagel

We present a systematic investigation of the distribution of normal forces at the boundaries of static packings of spheres. A method for the efficient construction of large hexagonal-close-packed crystals is introduced and used to study the effect of spatial ordering on the distribution of forces. Under uniaxial compression we find that the form for the probability distribution of normal forces...

Journal: :Physical review letters 2002
S Monastra F Manghi C A Rozzi C Arcangeli E Wetli H-J Neff T Greber J Osterwalder

The low-energy electronic excitations in cobalt are studied by a theoretical method that includes many-body effects and a realistic description of the band structure. Angle-resolved photoemission spectra measured on a thick film of hexagonal close-packed Co on Cu(111) agree well with calculated spectral functions. Because of many-body effects no sharp quasiparticle peaks exist for binding energ...

2005
Hans Koch Charles Radin Lorenzo Sadun

The hard sphere model is known to show a liquid-solid phase transition, with the solid expected to be either face centered cubic or hexagonal close packed. The differences in free energy of the two structures is very small and various attempts have been made to determine which structure is the more stable. We contrast the different approaches and extend one. 1 Research supported in part by NSF ...

Journal: :Physical review letters 2007
N Osterman D Babic I Poberaj J Dobnikar P Ziherl

We experimentally study the condensed phases of repelling core-softened spheres in two dimensions. The dipolar pair repulsion between superparamagnetic spheres trapped in a thin cell is induced by a transverse magnetic field and softened by suitably adjusting the cell thickness. We scan a broad density range and we materialize a large part of the theoretically predicted phases in systems of cor...

2006
Nicola Gaston Beate Paulus N. Gaston

Mercury condenses at 233 K into the rhombohedral structure with a bond length a = 3.005 Å and an angle of 70.53 . In contrast, zinc and cadmium adopt the hexagonal close-packed (hcp) structure, but with an anomolous c/a ratio which is far from ideal hcp. Density functional methods fail to describe either of these structures accurately. An application of the method of increments to these metals,...

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