نتایج جستجو برای: melting mechanism

تعداد نتایج: 591117  

Journal: :Physical review letters 2001
Z H Jin P Gumbsch K Lu E Ma

The atomic-scale details during melting of a surface-free Lennard-Jones crystal were monitored using molecular dynamics simulations. Melting occurs when the superheated crystal spontaneously generates a sufficiently large number of spatially correlated destabilized particles that simultaneously satisfy the Lindemann and Born instability criteria. The accumulation and coalescence of these intern...

2008
Leonid Burakovsky Dean L. Preston Richard R. Silbar

In the framework of melting as a dislocation-mediated phase transition we derive an equation for the pressure dependence of the melting temperatures of the elements valid up to pressures of order their ambient bulk moduli. Melting curves are calculated for Al, Mg, Ni, Pb, the iron group (Fe, Ru, Os), the chromium group (Cr, Mo, W), the copper group (Cu, Ag, Au), noble gases (Ne, Ar, Kr, Xe, Rn)...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2005
Vassili Ivanov Dmitri Piontkovski Giovanni Zocchi

We propose a statistical mechanics model for the melting transition of DNA. Base pairing and stacking are treated as separate degrees of freedom, and the interplay between pairing and stacking is described by a set of local rules which mimic the geometrical constraints in the real molecule. This microscopic mechanism intrinsically accounts for the cooperativity related to the free energy penalt...

2008
Leonid Burakovsky Dean L. Preston

The melting of elemental solids is modelled as a dislocation-mediated transition on a lattice. Statistical mechanics of linear defects is used to obtain a new relation between melting temperature, crystal structure, atomic volume, and shear modulus that is accurate to 17% for at least half of the Periodic Table.

Journal: :Journal of the Japan Society of Powder and Powder Metallurgy 1969

Journal: :Physical review letters 2008
C Hock S Straburg H Haberland B v Issendorff A Aguado M Schmidt

Melting-point depression by soluble impurities is an entropy-driven phenomenon. Studying partially oxidized free sodium nanoparticles, we found an additional mechanism, which is caused by insoluble impurities. Oxidization of sodium clusters with 135-192 atoms by a single oxygen molecule causes a melting-point depression of 17+/-6 K; additional oxygen amplifies the effect. This is in contrast to...

Journal: :International journal of numerical analysis and modeling 2009
Khawla Qamhieh Ka-Yiu Wong Gillian C Lynch B Montgomery Pettitt

The details of melting of DNA immobilized on a chip or nanoparticle determines the sensitivity and operating characteristics of many analytical and synthetic biotechnological devices. Yet, little is known about the differences in how the DNA melting occurs between a homogeneous solution and that on a chip. We used molecular dynamics simulations to explore possible pathways for DNA melting on a ...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2007
Santi Prestipino

Inverse melting is the phenomenon, observed in both helium isotopes, by which a crystal melts when cooled at constant pressure. I investigate discrete-space analogs of inverse melting by means of two instances of a triangular-lattice-gas system endowed with a soft-core repulsion and a short-ranged attraction. To reconstruct the phase diagram, I use both transfer-matrix and Monte Carlo methods, ...

Journal: :Science 2014
Amit Samanta Mark E Tuckerman Tang-Qing Yu Weinan E

The melting of a solid, like other first-order phase transitions, exhibits an intrinsic time-scale disparity: The time spent by the system in metastable states is orders of magnitude longer than the transition times between the states. Using rare-event sampling techniques, we find that melting of representative solids-here, copper and aluminum-occurs via multiple, competing pathways involving t...

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