A simple monatomic system in two dimensions with a double-well interaction potential is investigated in a wide range of temperatures by molecular-dynamics simulation. The system is melted and equilibrated well above the melting temperature, and then it is quenched to a temperature 88% below the melting temperature at several cooling rates to produce an amorphous state. Various thermodynamic qua...

Modern real-time PCR systems make it easy to monitor fluorescence while temperature is varied for hundreds of samples in parallel, permitting high-throughput studies. We employed such system to investigate melting transitions of ordered nucleic acid structures into disordered random coils. Fluorescent dye and quencher were attached to oligonucleotides in such a way that changes of fluorescence ...

We have investigated the phase diagram of Xe over a wide pressure-temperature range by molecular dynamics. The calculated melting curve is in good agreement with earlier experimental data. At a pressure of around 25 GPa and a temperature of about 2700 K we find a triple fcc-bcc liquid point. The calculated fcc-bcc boundary is in nice agreement with the experimental points, which, however, were ...

A molecular-dynamics technique is utilized to calculate the melting curve of submonolayer and complete layers of krypton atoms physisorbed onto a spherical substrate. Two models of the substrate are used. In the first model the substrate is treated as a spherical continuum whose differential elements interact with krypton atoms via Lennard-Jones ~LJ! potential. Hysteresis is present in the melt...

Heat capacities have been measured as a function of temperature for size-selected gallium cluster cations with between 60 and 183 atoms. Almost all clusters studied show a single peak in the heat capacity that is attributed to a melting transition. The peaks can be fit by a two-state model incorporating only fully solid-like and fully liquid-like species, and hence no partially melted intermedi...

The amorphous-to-microcrystalline phase transition of Ge in Pb/Ge multilayer geometry has been investigated as a function of layer thicknesses with the use of high-temperature x-raydiA'raction techniques. During crystallization, the modulation structure is destroyed and the Pb texture improves. In addition, the crystallization temperature decreases with decreasing amorphous Ge thickness and inc...

Aluminum nanocontact conductance histograms are studied experimentally from room temperature up to near the bulk melting point. The dominant stable configurations for this metal show a very early crossover from shell structures at low wire diameters to ionic subshell structures at larger diameters. At these larger radii, the favorable structures are temperature-independent and consistent with t...

The temperature of a Fe-Cr-Ni alloy (304 stainless steel) has been measured during shock compression using a high-speed radiometric technique. Experiments were performed on highquality thick films deposited on sapphire and LiF windows. The samples had no observable porosity or defects and closely meet the ideal criteria for shock temperature measurements. Data obtained with both A1203 and LiF w...

Two phenomena will be considered. Phase transformations (PTs) and chemical reactions (CRs) under compression and shear of materials in rotational diamond anvil cell (RDAC) represent examples of apparent effects of plastic shear. We recently predicted the new phenomenon that crystal-crystal and crystalamorphous PTs can occur through virtual melting (VM) significantly below (> 1000K!) the melting...

We have used classical molecular dynamics based on the Brenner potential describing carbon-carbon covalent bonds to study the melting point and vacancy movement in a rectangular graphene nanoribbon. The melting point of the graphene nanoribbon extracted from the numerical simulation is ~3400 K. We also found that two separated vacancies at high temperature (e.g., ~3000 K, below the melting poin...