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in subjects: "Lennard-Jones Potential"

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Structure from solute-solvent interactions in supercritical polyatomic molecular mixtures

Solute-solvent and solute-solute microstructures at the sueprcritical state are important in elucidating chemical reaction and spectroscopic data. We can classify the range of pair correlations into two regions: a short range (r {le} r{sub min}) and a long range (r from r{sub min} to 20 {approximately} 50 molecular diameters). The often cited local density enhacement referes to the short range corelations and is shown not to be related to the critical behavior of the mixture. The long-range beh… more

Date: December 31, 1994

Creator: Lee, L.L. & Cochran, H.D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Genetic algorithm optimization of atomic clusters

The authors have been using genetic algorithms to study the structures of atomic clusters and related problems. This is a problem where local minima are easy to locate, but barriers between the many minima are large, and the number of minima prohibit a systematic search. They use a novel mating algorithm that preserves some of the geometrical relationship between atoms, in order to ensure that the resultant structures are likely to inherit the best features of the parent clusters. Using this ap… more

Date: December 31, 1996

Creator: Morris, J. R.; Deaven, D. M.; Ho, K. M.; Wang, C. Z.; Pan, B. C.; Wacker, J. G. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Capillary Waves at Liquid/Vapor Interfaces: A Molecular Dynamics Simulation

Evidence for capillary waves at a liquid/vapor interface are presented from extensive molecular dynamics simulations of a system containing up to 1.24 million Lennard-Jones particles. Careful measurements show that the total interfacial width depends logarithmically on L{sub {parallel}}, the length of the simulation cell parallel to the interface, as predicted theoretically. The strength of the divergence of the interfacial width on L{sub {parallel}} depends inversely on the surface tension {ga… more

Date: July 16, 1999

Creator: Sides, Scott W.; Grest, Gary S. & Lacasse, Martin-D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Molecular dynamics for 400 million particles with short-range interactions

We report the design and performance of a computational molecular dynamics (MD) code for 400 million particles interacting through the standard pairwise 6-12 Lennard-Jones potential on a 1024-node Intel Paragon, a distributed-memory MIMD parallel computer. The initially recorded {open_quotes}particle-step time{close_quotes} was .4 microseconds. A new inter-node communication strategy ensures high parallel efficiency for a large number of nodes. Besides the ability to tackle large problems, our … more

Date: July 1995

Creator: Deng, Y.; McCoy, R. A. & Marr, R. B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Large scale simulations of melting in two dimensional Lennard-Jones systems: Evidence for a metastable hexatic phase

In 1995, North Americans installed $5 billion in efficiency equipment in their buildings in order to save money and conserve energy and water. But this covers only a small fraction of the existing cost-effective opportunities for energy savings investments. If all cost-effective efficiency investments were made in public and commercial buildings, the United States would save $20 billion per year on energy bills, create over 100,000 jobs, and significantly cut pollution. When firms invest in ene… more

Date: March 1, 1996

Creator: Chen, K.; Kaplan, T. & Mostoller, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Determination of interionic potentials in molecules

The rationale underlying materials by design is that properties are determined by structure so that if the relationships between structure and properties are understood, an appropriate material can be designed and fabricated to meet any set of criteria. Since ion-ion potentials determine state transformations and reactivity, they are essential to the entire concept of materials and molecules by design. Virtually all of the important state-to-state processes undergone by molecules (excitation, r… more

Date: April 1, 1996

Creator: Conradson, S.D.; Leon, J.M. & Bridges, F.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

A new shared-memory programming paradigm for molecular dynamics simulations on the Intel Paragon

This report describes the use of shared memory emulation with DOLIB (Distributed Object Library) to simplify parallel programming on the Intel Paragon. A molecular dynamics application is used as an example to illustrate the use of the DOLIB shared memory library. SOTON-PAR, a parallel molecular dynamics code with explicit message-passing using a Lennard-Jones 6-12 potential, is rewritten using DOLIB primitives. The resulting code has no explicit message primitives and resembles a serial code. … more

Date: December 1, 1994

Creator: D`Azevedo, E.F. & Romine, C.H.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Molecular dynamic studies of crack propagation. The role of the interatomic potential

We have used the molecular dynamic simulation technique in studying a variety of solid state problems, ranging from equation-of-state and shock wave propagation to epitaxy and various aspects of crack propagation. In these simulations, which are classical, Newton's equations-of-motion are solved for each particle at every step to yield positions, velocities, forces and energies. An important limitation of the technique is that one has to put an interatomic potential into the calculation. Within… more

Date: January 1, 1986

Creator: Dienes, G.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Cool Cluster Correctly Correlated

Atomic clusters are unique objects, which occupy an intermediate position between atoms and condensed matter systems. For a long time it was thought that physical and chemical properties of atomic dusters monotonically change with increasing size of the cluster from a single atom to a condensed matter system. However, recently it has become clear that many properties of atomic clusters can change drastically with the size of the clusters. Because physical and chemical properties of clusters can… more

Date: December 17, 2005

Creator: Varganov, Sergey Aleksandrovich

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

open access

RISM theory distribution functions for Lennard--Jones interaction site fluids

Reference interaction site model (RISM) theory distribution functions for Lennard-Jones interaction site fluids are discussed. The comparison with computer simulation results suggests that these distribution functions are as accurate as RISM distribution functions for fused hard sphere molecular fluids.

Date: January 1, 1978

Creator: Johnson, E. & Hazoume, R.P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Composition dependence of fluid thermophysical properties: Theory and modeling. Progress report

Objectives are studies of equilibrium/nonequilibrium properties of asymmetric fluid mixtures through computer simulation (CS), development of predictive theories of mixture equilibrium properties, development and application of selection algorithm methodology for mixture equations of state, and use of theory to develop new engineering design models for fluid mixtures. Kirwood charging method CS of Lennard-Jones mixtures with large size ratios verified the Kirkwood-Buff/Baxter method of calculat… more

Date: March 29, 1993

Creator: Ely, J. F.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

A massively parallel algorithm for grand canonical Monte Carlo computer simulation with the short-ranged Lennard-Jones potential

We present a new massively parallel decomposition for grand canonical Monte Carlo computer simulation (GCMC) suitable for short ranged fluids. Our spatial algorithm relies on the fact that for short-ranged fluids, molecules separated by a greater distance than the reach of the potential act independently, thus different processors can work concurrently in regions of the same system which are sufficiently far apart. Several parallelization issues unique to GCMC are addressed such as the handling… more

Date: May 1, 1994

Creator: Heffelfinger, G. S. & Lewitt, M. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Phenomenological explanation of elastic anomalies in superlattices

The experimental fact that measured elastic and structural properties of superlattices are strongly correlated can be understood on the basis of a simple model based on the packing of hard spheres. The model is consistent with features of many models that have been proposed to explain the supermodulus effect; but contrary to previous explanations, it allows predictions for a given pair of constitutents to be made. For an arbitrary pair of elements, it predicts the existence or non-existence of … more

Date: June 1, 1993

Creator: Grimsditch, M.; Fullerton, E. E. & Schuller, I. K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

[Adsorption and diffusion of fluids in well-characterized adsorbent materials]. Annual technical progress report, September 1, 1988--July 31, 1991

This grant covers theoretical and molecular simulation studies in two areas: the thermodynamic behavior of associating liquids and their mixtures in the bulk phase, and the behavior of fluids in narrow pores. Fluids of longer chains are being simulated to test the perturbation theory. The Helmholtz free energy equation with the first order theory for association was applied to a wide variety of pure and mixed fluids; good agreement with experiment was found. In the second area, the nonlocal for… more

Date: December 31, 1991

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

A database of selected transport coefficients for combustion studies

COYOTE and similar combustion programs based on the multicomponent Navier-Stokes equations require the mixture viscosity, thermal conductivity, and species transport coefficients as input. This report documents a significant improvement to the calculation of these molecular transport coefficients in COYOTE and provides a self-contained and easy-to-use source of such data in a format suitable for use by such programs. We present the data for various species in two forms. The first is a simple fu… more

Date: August 1, 1993

Creator: Cloutman, L. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

A simple real space density functional theory of freezing, with implications for the glass transition

With analogy to the ''highly accurate'' summation of cluster diagrams for hard sphere fluids a la Carnahan-Starling, we present a simple, real space free energy density functional for arbitrary potential systems, based on the generalization of the second virial coefficient to inhomogeneous systems which, when applied to hard sphere, soft-sphere, and Lennard-Jones freezing, yield melting characteristics in remarkable agreement with experiment. Implications for the liquid-glass transition in all … more

Date: January 1, 1989

Creator: Stoessel, J.P. & Wolynes, P.G.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Calculation of the mean force constants of the rare gases and the rectilinear law of mean force

The mean energies, (U), and the mean force constants, (nabla/sup 2/U), have been calculated for liquid argon and liquid krypton using the WCA perturbation theory, and for gaseous argon and krypton along the coexistence line by solution of the PY equation for the radial distribution function. Calculations have been made for the Lennard-Jones, Barker-Henderson, and Maitland-Smith potentials. There is little difference in the values of (U) and (nabla/sup 2/U) calculated for the three potentials. T… more

Date: January 1, 1977

Creator: Lee, M. W. & Bigeleisen, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

FORTRAN Programs for Computing Angular Distributions and Q Values of Nuclear Reactions

Three Fortran programs, written for the IBM-704 computer, process the data from multichannel pulse-height analyzers in order to derive the Q values and differential cross sections of the groups observed. The standard deviations of the derived Q values and of the differential cross sections are also computed. With another program that was written, the effects of impurities can be subtracted from pulse-height spectra observed when a target contains a mixture of nuclides. A fifth program computes … more

Date: May 1, 1963

Creator: Broek, H.W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Lattice dynamics of neon at high pressure. [Phonon dispersion relations; Grueneisen parameter]

The phonon dispersion relations in a high-density Ne crystal have been measured in the (110),(110), and (111) symmetry directions at 8K using a triple-axis neutron spectrometer. The crystal was grown at a pressure of 6 kbar and at 82K in a new high pressure sample holder. A Born--von Karman force constant analysis indicated that the interatomic forces in Ne remain predominantly central in nature at this density. The data were found to be well represented in the harmonic approximation by a Lenna… more

Date: January 1, 1976

Creator: Eckert, J.; Axe, J. D. & Daniels, W. B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Some aspects of equations of state. [Detonating gases; repulsive paint centers or hard-sphere fluid]

Some elementary properties of the equation of state of molecules repulsing each other as point centers of force are developed briefly. An inequality for the Lennard--Jones gas is presented. The scaled particle theory equation of state of hard spheres is also reviewed briefly. Means of possibly applying these concepts to represent thermodynamic data on model detonating gases are suggested.

Date: February 1, 1979

Creator: Frisch, H.L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Vacancy behavior in a compressed fcc Lennard-Jones crystal

This computer experiment study concerns the determination of the stable vacancy configuration in a compressed fcc Lennard-Jones crystal and the migration of this defect in a compressed crystal. Isotropic and uniaxial compression stress conditions were studied. The isotropic and uniaxial compression magnitudes employed were 0.94 less than or equal to eta less than or equal to 1.5, and 1.0 less than or equal to eta less than or equal to 1.5, respectively. The site-centered vacancy (SCV) was the s… more

Date: December 1, 1981

Creator: Beeler, J.R. Jr.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Nonequilibrium Molecular Dynamics

The development of nonequilibrium molecular dynamics is described, with emphasis on massively-parallel simulations involving the motion of millions, soon to be billions, of atoms. Corresponding continuum simulations are also discussed. 14 refs., 8 figs.

Date: November 1, 1990

Creator: Hoover, W.G. (California Univ., Davis, CA (USA). Dept. of Applied Science Lawrence Livermore National Lab., CA (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Approximate Phonon Frequency Distributions for FCC Lennard--Jones Harmonic Crystals.

No Description Available.

Date: January 1, 1972

Creator: Pollock, E. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

DOE/NNSA/DE-FG03-03NA00069 Annual Report 1

OAK-B135 This project was undertaken to enhance our understanding and control of the response of ductile materials to extreme loading conditions such as those involved in impact loading. The project was designed with a focus on the role of friction in high rate deformation and shock studies. The work involves collaboration of the tribology group in Materials Science and Engineering at OSU and two groups at LANL, an impact loading group in the dynamic experimentation division and a computer simu… more

Date: March 13, 2004

Creator: Rigney, David A.

Item Type: Report

Partner: UNT Libraries Government Documents Department