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Elastic moduli and dislocation core energy of the triangular solid of hard disks of diameter σ are obtained in the limit of vanishing dislocationantidislocation pair density, from Monte Carlo simulations which incorporates a constraint, namely that all moves altering the local connectivity away from that of the ideal triangular lattice are rejected. In this(More)
The reverse martensitic (“austenitic”) transformation upon heating of equiatomic nickeltitanium nanoparticles with diameters between 4 and 17 nm is analyzed by means of molecular-dynamics simulations with a semi-empirical model potential. After constructing an appropriate order parameter to distinguish locally between the monoclinic B19′ at low and the(More)
The possibility of fabricating electronic devices with functional building blocks of atomic size is a major driving force of nanotechnology. The key elements in electronic circuits are switches, usually realized by transistors, which can be configured to perform memory operations. Electronic switches have been miniaturized all the way down to the atomic(More)
Elastic constants of two-dimensional (2D) colloidal crystals are determined by measuring strain fluctuations induced by Brownian motion of particles. Paramagnetic colloids confined to an air-water interface of a pendant drop are crystallized under the action of a magnetic field, which is applied perpendicular to the 2D layer. Using video microscopy and(More)
Many experiments have shown that the conductance histograms of metallic atomic-sized contacts exhibit a peak structure, which is characteristic of the corresponding material. The origin of these peaks still remains as an open problem. In order to shed some light on this issue, we present a theoretical analysis of the conductance histograms of Au atomic(More)
We investigate the properties of membranes under tension by Monte Carlo simulations of a generic coarse-grained model for lipid bilayers. We give a comprising overview of the behavior of several membrane characteristics, such as the area per lipid, the monolayer overlap, the nematic order, and pressure profiles. Both the low-temperature regime, where the(More)
F. Pauly,1,2,* M. Dreher,3 J. K. Viljas,1,2 M. Häfner,1,2 J. C. Cuevas,1,2,4 and P. Nielaba3 1Institut für Theoretische Festkörperphysik, Universität Karlsruhe, D-76128 Karlsruhe, Germany 2Forschungszentrum Karlsruhe, Institut für Nanotechnologie, D-76021 Karlsruhe, Germany 3Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany 4Departamento(More)
We report conductance and thermopower measurements of metallic atomic-size contacts, namely gold and platinum, using a scanning tunneling microscope (STM) at room temperature. We find that few-atom gold contacts have an average negative thermopower, whereas platinum contacts present a positive thermopower, showing that for both metals, the sign of the(More)
The nature of freezing and melting transitions for a system of hard disks in a spatially periodic external potential is studied using extensive Monte Carlo simulations. Detailed finite size scaling analysis of various thermodynamic quantities like the order parameter, its cumulants, etc., are used to map the phase diagram of the system for various values of(More)