A fine Au powder, with a mean particle diameter of 4 nm, has been successfully fabricated. The crystalline structure the nm nanoparticles remains in fcc symmetry. No structural changes were found between 15 and 450 K. crossover from positive thermal expansion at low temperatures to negative high was observed cell parameter about 125 Anomalies associated also magnetic response heat capacity measurements. observations can be reasonably well interpreted by accounting for effects valence...

In this work, we present modifications to the well-known basin hopping (BH) optimization algorithm [D. J. Wales and P. Doye, Phys. Chem. A 101, 5111 (1997)] by incorporating in it unique specific nature of interactions among valence electrons ions carbon atoms through calculating cluster’s total energy density functional tight-binding (DFTB) theory, using find lowest structures clusters and, from these optimized atomic electronic structures, studying their varied forms topological...

We report an optimization algorithm for studying bimetallic nanoclusters. The combines two state-of-the-art methods, the genetic and basin hopping approach, widely employed in literature predicting structures of pure metallic nonmetallic clusters. To critically test present its use determining lowest-energy nanoclusters, we apply it to study clusters Cu(n)Au(38-n) (0< or =n< =38). It is predicted that Au atoms, being larger size than Cu prefer occupy surface sites showing thus segregating...

We present detailed numerical results on the ground state structures of metallic clusters. The Gupta-type many-body potential is used to account for interactions between atoms in cluster. Both genetic algorithm technique and basin hopping method have been applied search global energy minima excellent agreement found both schemes gives credence optimized values obtained. For four monovalent one polyvalent metals studied this work within accuracy energies presented here, we find that predicted...

The multicanonical basin hopping (MUBH) method, which uses a weight in the (BH) Monte Carlo was found to be very efficient for global optimization of large-scale systems such as Lennard-Jones clusters containing more than 150 atoms. We have implemented an asynchronous parallel version MUBH method using message passing interface (MPI) take advantage full usage multiprocessors either homogeneous or heterogeneous computational environment. Based on intrinsic properties this MPI implementation...

We grew graphene epitaxially on 6H-SiC(0001) substrate by the simulated annealing method. The mechanisms that govern growth process were investigated testing two empirical potentials, namely, widely used Tersoff potential [J. Tersoff, Phys. Rev. B 39, 5566 (1989)] and its more refined version published years later Erhart Albe [Phys. 71, 035211 (2005)]. Upon contrasting results obtained these we found proposed is generally physical realistic, since temperature at which structure just coming...

We introduce a new optimization algorithm that combines the basin-hopping method, which can be used to efficiently map out an energy landscape associated with minima, multicanonical Monte Carlo encourages system move of traps during computation. As example implementing for global minimization multivariable system, we consider Lennard-Jones systems containing 150-185 particles, and find is more efficient than original method.

The isothermal Brownian-type molecular dynamics simulation has been applied to study the melting behavior of bimetallic clusters. It was found that specific heat and Lindermann-like parameter customarily used in bulk system describe solid-liquid transition show incongruity predicted temperature Tmelt. underlying mechanisms lead incompatibility Tmelt separately deduced from these two quantities were analyzed further. To gain insight into behavior, we calculated addition velocity...

We perform isothermal Brownian-type molecular dynamics simulations to obtain the velocity autocorrelation function and its time Fourier-transformed power spectral density for metallic cluster Ag(17)Cu(2). The temperature dependences of these dynamical quantities from T = 0 1500 K were examined across this range melting T(m), which we define be principal maximum position specific heat is determined. instantaneous normal mode analysis then used dissect by calculating vibrational states hence...

The Brownian-type molecular dynamics simulation is revisited and applied to study the thermal geometric properties of four mono- two polyvalent metallic clusters. For property, we report specific heat at constant volume CV solid-liquid-like transition by scrutinizing its characteristic. calculate root mean square relative bond-length fluctuation delta as a function increasing temperature. change in reflects movement atoms hence relevant parameter understanding phase simulated results for...

We report a Brownian isothermal molecular dynamics simulation study of bimetallic clusters. Beginning at their lowest energy structures which were obtained from recently developed algorithm [P. J. Hsu and S. K. Lai, Chem. Phys. 124, 044711 (2006)], we investigate the effect temperature on thermal geometric ${\mathrm{Cu}}_{m}{\mathrm{Au}}_{n\ensuremath{-}m}$ given nuclearity $n$. in particular change relative root-mean-squared bond length fluctuation $\ensuremath{\delta}$ so-called Lindemann...

This paper studies the melting behavior of Ag(14) cluster employing instantaneous normal mode (INM) analysis that was previously developed for bimetallic Ag(17)Cu(2). The isothermal Brownian-type molecular dynamics simulation is used to generate atom configurations at different temperatures up 1500 K. At each temperature, these atomic are then analyzed by INM technique. To delve into which differs from Ag(17)Cu(2) occurrence an anomalous prepeak in specific heat curve addition typical...

We apply equilibrium and nonequilibrium molecular dynamics simulations to study the dynamic properties of electrolytes in nanopores. The realistic primitive model restrictive widely used statistical mechanics liquid-state theory are applied electrolytes. electrolytic ions immersed water, treated this work as either a dielectric continuum ignoring size solvent molecules or macroscopic (polar property) plus neutral soft spheres, aqueous electrolyte is put confined space. To simulate condition...

The isothermal Brownian-type molecular dynamics simulation was applied to study the melting scenario of noble-metal-based bimetallic clusters. failure results portend a compatible temperature, Tmelt, which is defined in specific heat CV at its principal peak and Lindermann-like parameter temperature it exhibits drastic change, has prompted us calculate velocity autocorrelation function VACF or Fourier-transform, power spectrum as another useful variable for describing cluster melting. Two...

Improved basis sets for the study of polymer dynamics by means diffusion theory, and tests on a melt cis-1,4-polyisoprene decamers, toluene solution 71-mer syndiotactic trans-1,2-polypentadiene were presented recently [R. Gaspari A. Rapallo, J. Chem. Phys. 128, 244109 (2008)]. The proposed hybrid approach (HBA) combined two techniques, long time sorting procedure maximum correlation approximation. HBA takes advantage strength these its proved to be very effective computationally convenient...

Folded conformations of proteins in thermodynamically stable states have long lifetimes. Before it folds into a conformation, or after unfolding from the protein will generally stray one random conformation to another leading thus rapid fluctuations. Brief structural changes therefore occur before folding and events. These short-lived movements are easily overlooked studies folding/unfolding for they represent momentary excursions explore neighborhood conformation. The present study looks...

The Gupta-type many-body potential was applied to describe the interactions between atoms in zinc nanoclusters. From calculated ground state structures, obtained by Brownian-type molecular dynamic simulation, we investigated temperature effect of clusters. We studied particular constant volume specific heat CV which is a thermodynamic quantity and also relative bond length Lindemann parameter δ geometric quantity. Effort devoted revealing anomalies observed these quantities for Zn clusters...

A recently developed modified basin hopping (MBH) optimization algorithm, combined with an energy function calculated by the semiempirical density functional tight-binding (DFTB) theory, was applied to determine lowest-energy structures of Aun clusters size n = 3-20. It predicted from DFTB/MBH algorithm calculations that Au10, Au15, and Au18 exhibit chiral properties; i.e., each these three possesses same value associated it are two nonsuperposable mirror-image clusters. In potential...

The present work is devoted to extracting the energy or enthalpy distribution function of a physical system from moments using maximum entropy method. This theory has salient traits that it utilizes only experimental thermodynamic data. calculated functions provide invaluable insight into state phase behavior systems under study. As concrete evidence, we demonstrate elegance by studying first test case two-dimensional six-state Potts model for which simulation results are available...