Showing papers on "Dynamic Monte Carlo method published in 1971"

Monte carlo channeling calculations.

Abstract: A Monte Carlo computer program for following the trajectories of high-energy ions in a lattice has been used to study depth dependence, half-angles, and minimum yields in channeling. The program uses the Thomas-Fermi interaction between ions and lattice atoms and gives the atoms' independent thermal displacements appropriate to the temperature of the lattice. The depth dependence of the nuclear interaction probability near the surface has been calculated and shown to be of importance in understanding other phenomena as well as having an intrinsic interest. Extensive calculations to explore the temperature and energy dependences of half-angles and minimum yields were done, and analytical formulas are given that summarize the computer results. The half-angle formulas give generally improved agreement with experiment and resolve certain discrepancies noted by Picraux, Davies, Eriksson, Johansson, and Mayer between their measurements and earlier theories. Minimum yields were calculated for both single- and double-alignment configurations. The results reveal an energy dependence as well as giving a better description of the temperature dependence and improved agreement with experiment. A relationship is given between the minimum yield and the yield from the surface.

Liquid argon: Monte carlo and molecular dynamics calculations

Abstract: Thermodynamic properties of liquid argon are calculated by Monte Carlo and molecular dynamics techniques, using accurate pair-potential functions determined from the properties of solid and gaseous argon, together with the Axilrod-Teller three-body interaction. Satisfactory techniques for evaluating three-body contributions to thermodynamic properties without excessive requirements of computer time are described. Quantum corrections are included. Agreement with experiment is excellent: the best pair and triplet potentials give an excellent description of the properties of solid, gaseous and liquid argon.

Conditional Monte Carlo: A Simulation Technique for Stochastic Network Analysis

Abstract: This paper is concerned with a simulation procedure for estimating the distribution functions of the time to complete stochastic networks. The procedure, called conditional Monte Carlo, is shown to be substantially more efficient (in terms of the computational effort required) than traditional simulation methods. The efficacy of conditional Monte Carlo and its use in conjunction with other Monte Carlo methods is illustrated for the Wheatstone bridge network. The applicability of the procedure to larger networks, as well as other stochastic systems, is discussed, and a general method is given for its implementation.

Monte Carlo Principles and Neutron Transport Problems

Abstract: (1971). Monte Carlo Principles and Neutron Transport Problems. Nuclear Science and Engineering: Vol. 46, No. 3, pp. 439-440.

Monte Carlo Calculation of the Transient Photocurrent in Low-Carrier-Mobility Materials

Abstract: A Monte Carlo method is used to calculate the shape of the transient photocurrent under flash excitation. It is shown that some of the anomalous features of the experimental data can be explained by including surface as well as bulk trapping in the model. In particular, this simple picture predicts the observed long tail of the pulse as well as the apparent field dependence of the mobility.

Monte Carlo Calculation of Hot Electron Phenomena. I. Streaming in the Absence of a Magnetic Field

Abstract: Hot electron phenomena in p -type germanium are investigated by using a Monte Carlo method. The variation of the distribution function and other properties is examined for various temperatures and impurity densities, and for a wide electric field range. Some characteristic features proper to the streaming state are described with emphasis.

Monte Carlo of Chains with Excluded Volume: Distribution of Intersegmental Distances

Abstract: A Monte Carlo study of non‐self‐intersecting chains on a four‐choice cubic lattice is undertaken with the help of a recently described “dimerization” method. This method permits to avoid the difficulty of “sample attrition,” enabling the construction of relatively long chains. Certain improvements of the method are described and its validity is substantiated. The distribution and average values of the end to end, as well as of various intrachain distances, are determined for chain lengths varying from N = 32 to 8192. The results indicate that the basic assumptions of several theories on excluded volume need to be revised.

The Monte Carlo Method

Abstract: We give here a detailed technical description of a Monte Carlo scheme for the dynamical evolution of spherical stellar systems The philosophy of the method, as well as a few illustrative results, are given elsewhere (Henon, 1972, hereafter called I)

Bounded estimators for flux at a point in monte carlo.

Abstract: Methods are given for obtaining bounded estimators for radiation flux at a point detector in a Monte Carlo calculation. In essence, the procedure is to so bias the collision density in the neighbor...

Comparison of Classical Monte Carlo Experiments with Improved Self-Consistent Phonon Theory: Thermodynamic Properties of Solid Xe

Abstract: The improved self-consistent phonon theory (ISC) is compared with classical Monte Carlo experiments for a model approximating solid Xe. A Lennard-Jones (LJ) (12-6) nearest-neighbor (nn) potential is used to calculate the lattice constant, expansivity, ${C}_{v}$, ${C}_{p}$, the bulk modulus, and the thermodynamic Gr\"uneisen parameter. The ISC is found to be only semiquantitative at high temperatures. By comparing the Monte Carlo results for high temperature and the ISC for low temperature with experiment we can see deficiencies in our simple nn model of the interatomic forces in solid Xe.

A New Multistage Procedure for Systematic Variance Reduction in Monte Carlo

Abstract: A common technique in Monte Carlo applications is to introduce into the simulation one or more parameter values whose purpose is to lower the variance in the estimated quantity without affecting its mean. Good parameter choices may sometimes be guessed or found by using physical insight, but to date, no way has been described systematically to find parameter choices which minimize the variance. This paper develops a multistage technique for accomplishing this optimization. The technique is based on obtaining very efficient estimates of the relative parametric dependence of the variance by averaging random variables over a small number of samples chosen with fixed, but arbitrary, parameter values. The utility of the method is illustrated by applying it to the optimization of the exponential transform, a variance-reducing technique which is often used in shielding calculations.

Efficient Monte Carlo Generation of Self‐Avoiding Polymers

Abstract: A new method for generating self‐avoiding random polymers is described. Utilization of this method makes the total time spent on double occupancy checking during the development of a self‐avoiding polymer, in principle, only linearly dependent on the length. To test the method, self‐avoiding polymers of 14 to 200 bonds have been developed on the tetrahedral lattice by Monte Carlo techniques. Properties of the distribution of polymers obtained are presented, and these properties are shown to be consistent with previously reported results.

Comparison of Classical Monte Carlo Experiments with Self-Consistent Phonon Theory: Elastic Constants for Solid Xenon

Abstract: Elastic constants from Monte Carlo computer experiments are compared with values calculated by self-consistent phonon theory for a model approximating fcc solid Xe. We have used a Lennard-Jones (12-6) nearest-neighbor potential which gives a fair account of the thermodynamics. Adiabatic elastic constants obtained by both methods are in good agreement. Comparison is also made with recent experimental elastic-constant data of Gornall and Stoicheff.

Techniques in Monte Carlo Analysis Applied to the Nuclear Density Gauge

Abstract: The response of the Hidrodensimeter (HDM) nuclear density gauge for measuring road surface density is investigated by the Monte Carlo (stochastic) method. Special attention is paid to the effect of...