Showing papers on "Monte Carlo molecular modeling published in 1985"
TL;DR: In this article, the authors proposed and discussed a type of new robust estimators for covariance/correlation matrices and principal components via projection-pursuit techniques, which are of both rotational equivariance and high breakdown point.
Abstract: This article proposes and discusses a type of new robust estimators for covariance/correlation matrices and principal components via projection-pursuit techniques. The most attractive advantage of the new procedures is that they are of both rotational equivariance and high breakdown point. Besides, they are qualitatively robust and consistent at elliptic underlying distributions. The Monte Carlo study shows that the best of the new estimators compare favorably with other robust methods. They provide as good a performance as M-estimators and somewhat better empirical breakdown properties.
297 citations
TL;DR: In this paper, a statistical formulation of the multifragmentation of finite nuclei is given, which considers the generalization of the liquid-drop model for hot nuclei and allows one to calculate thermodynamic quantities characterizing the nuclear ensemble at the disassembly stage.
294 citations
TL;DR: In this paper, a square-lattice model of an amphiphile-oil-water system is developed in which oil and water molecules occupy single sites and amphiphiles occupy chains of sites.
Abstract: A square‐lattice model of amphiphile‐oil–water systems is developed in which oil and water molecules occupy single sites and amphiphiles occupy chains of sites. Energies and free energies estimated by Monte Carlo sampling of configuration space show that when the head, or water‐loving portion, of the amphiphile has no tendency to hydrate or surround itself with water, as opposed to surrounding itself with other heads, the capability of even long amphiphiles to solubilize repellant oil and water into a single phase is weak. Although the Monte Carlo free energies deviate markedly from those given by quasichemical theory, the deviation of the phase behavior is modest. Computer drawings of typical equilibrium configurations show highly irregular interfaces, apparently caused by capillary waves which are pronounced in two dimensions.
281 citations
TL;DR: Transfer-matrix methods for quantum spin systems are formulated and their limiting properties are studied rigorously and an implementation of the two-dimensional triangular antiferromagnetic quantum Heisenberg model is proposed.
Abstract: Transfer-matrix methods for quantum spin systems are formulated and their limiting properties are studied rigorously. The present formulation is applied explicitly to an exactly soluble transverse Ising model. A computer implementation of the two-dimensional triangular antiferromagnetic quantum Heisenberg model is also proposed to study Anderson's picture of the dynamic coherence of the phase of singlet pairs.
269 citations
TL;DR: In this article, an algorithm to include the Pauli exclusion principle in the Ensemble Monte Carlo method was presented, which indicates that significant changes in the transport properties of GaAs have to be expected when degenerate conditions are reached.
Abstract: An algorithm to include the Pauli exclusion principle in the Ensemble Monte Carlo method is presented. The results indicate that significant changes in the transport properties of GaAs have to be expected when degenerate conditions are reached. Important repercussions should be found in the modeling of microwave devices, where one often deals with highly doped regions.
261 citations
TL;DR: In this paper, an improved method for generating configurations according to the SU(2) heatbath distribution, which is also a central component of the SI(3) “quasi-heatbath” method of Cabibbo and Marinari, is presented.
237 citations
TL;DR: In this article, a new sampling technique, called staging, is introduced to circumvent the problem of high attrition rates in the isomorphic classical system, and allowed configurations are constructed with the use of a staging technique.
Abstract: We introduce a new sampling technique, called staging, which is likely to have applicability in the Monte Carlo evaluation of path integrals. In order to circumvent the problem of high attrition rates in the isomorphic classical system, allowed configurations are constructed with the use of a staging technique (algorithm). To illustrate the utility of this approach, the method is applied to a single quantum particle in a rigid bcc hard-sphere lattice and in a disordered system of fixed hard spheres.
181 citations
TL;DR: In this paper, the possible form of hyperscaling violations in finite-size scaling theory is discussed and the implications for recent tests in Monte Carlo simulations of the d = 3 Ising model are examined.
Abstract: The possible form of hyperscaling violations in finite-size scaling theory is discussed. The implications for recent tests in Monte Carlo simulations of the d = 3 Ising model are examined, and new results for the d = 5 Ising model are presented.
143 citations
TL;DR: In this article, the γ-expansion as introduced by Barboy and Gelbart is applied to a system of hard ellipsoids-of-revolution, and the expansion is truncated after the third order term yielding an approximate theory requiring the second and third-virial coefficients as inputs.
Abstract: The γ-expansion as introduced by Barboy and Gelbart is applied to a system of hard ellipsoids-of-revolution. The expansion is truncated after the third order term yielding an approximate theory requiring the second- and third-virial coefficients as inputs. As the third virial coefficient is not known analytically, numerical results are obtained for this quantity. The equation of state is obtained from a free-energy variational calculation. The results are compared with Monte Carlo data taken from the preceding paper in this series. The application of scaled particle theory to the same system is discussed, and shown to have serious shortcomings.
139 citations
TL;DR: In this paper, a review of recent developments in computational methods for quantum statistical lattice problems is presented, where the generalized Trotter formula is applied to the one-dimensional Ising model in a transverse field.
138 citations
TL;DR: In this article, a simplifled microscopic model is proposed for the gas-solid thermochromatography in open columns with the laminar flow of the carrier gas, which describes the downstream migration of a sample molecule as a rather small number of some effective random displacements, and sequences of adsorptiondesorption events that occur without changing the coordinates.
Abstract: A simplifled microscopic model is proposed for the gas-solid thermochromatography in open columns with the laminar flow of the carrier gas. This model describes the downstream migration of a sample molecule as a rather small number of some effective random displacements, and sequences of adsorptiondesorption events that occur without changing the coordinates. The relevant probability density distributions are thereby derived, Based on this model, a versatile Computer program has been developed for simulating the profiles of thermochromatographic zones by employing the Monte Carlo technique. Some results of these simulations are given to demonstrate the influence of several parameters on the zone profile.
TL;DR: It is shown that fluctuation renormalization techniques provide an effective means for treating the effects of high-order Fourier contributions.
Abstract: Monte Carlo Fourier path-integral techniques are explored. It is shown that fluctuation renormalization techniques provide an effective means for treating the effects of high-order Fourier contributions. The resulting formalism is rapidly convergent, is computationally convenient, and has potentially useful variational aspects.
TL;DR: In this article, a review of Monte Carlo methods for many-body systems is presented, with a particular emphasis on problems illustrating general progress in the implementation of the method and in the analysis of the results.
TL;DR: In this paper, the Metropolis algorithm has been generalized to allow for the variation of shape and size of the MC cell and a restricted MC integration in the nine dimensional space of the cell components also leads to the stable structure for the Lennard-Jones potential.
Abstract: The Metropolis algorithm has been generalized to allow for the variation of shape and size of the MC cell. A calculation using different potentials illustrates how the generalized method can be used for the study of crystal structure transformations. A restricted MC integration in the nine dimensional space of the cell components also leads to the stable structure for the Lennard-Jones potential.
TL;DR: In this paper, the connection between diffusion-limited aggregation and the equations of dendritic growth is critically examined, and a different type of Monte Carlo simulation is proposed and used to construct two-dimensional dendrite-like patterns.
Abstract: The connection between diffusion-limited aggregation and the equations of dendritic growth is critically examined. A different type of Monte Carlo simulation is proposed and used to construct two-dimensional dendrite-like patterns. The wavelength occurring for short times is in good agreement with the linear stability analysis. The time dependence of the characteristic wavelengths is also determined.
TL;DR: A new Monte Carlo method is introduced which generates configurations according to any desired probability distribution, unlike previous techniques, which require the relative probability of any two configurations to be computed exactly.
Abstract: A new Monte Carlo method is introduced which generates configurations according to any desired probability distribution. Unlike previous techniques, which require the relative probability of any two configurations to be computed exactly, this method allows the prescence of large but unbiased noise in this computation. The method has important applications in including the effects of dynamical fermions in Monte Carlo calculations, amongst other problems.
TL;DR: In this paper, the chemical potential of a fluid can be determined in a Monte Carlo simulation by gradually turning on or off the interaction of one particle with the other particles, which can be employed at densities where a direct use of the Widom formula is impractical.
Abstract: The chemical potential of a fluid can be determined in a Monte Carlo simulation by gradually turning on or off the interaction of one particle with the other particles. This method, which can be employed at densities where a direct use of the Widom formula is impractical, has been tested on a two-dimensional fluid of particles with a Lennard-Jones pair interaction.
TL;DR: The basic ideas and principles of Monte Carlo calculations are presented in the form of a "primer" for health physicists, and some of the more sophisticated techniques used in practice to reduce variance and computing time are described.
Abstract: The basic ideas and principles of Monte Carlo calculations are presented in the form of a primer for health physicists. A simple integral with a known answer is evaluated by two different Monte Carlo approaches. Random number, which underlie Monte Carlo work, are discussed, and a sample table of random numbers generated by a hand calculator is presented. Monte Carlo calculations of dose and linear energy transfer (LET) from 100-keV neutrons incident on a tissue slab are discussed. The random-number table is used in a hand calculation of the initial sequence of events for a 100-keV neutron entering the slab. Some pitfalls in Monte Carlo work are described. While this primer addresses mainly the bare bones of Monte Carlo, a final section briefly describes some of the more sophisticated techniques used in practice to reduce variance and computing time.
TL;DR: In this article, the authors described a method by which the short-time Green's function Monte Carlo solution to the many-body Schrodinger equation can be used to calculate directly the energy difference between two related systems.
TL;DR: This paper presented a study of small-sample properties for six criteria with Monte Carlo methods, and found that no criterion performs well, and that underfitting of models may be quite common.
TL;DR: In this article, the authors applied Quantum Monte Carlo (QMC) methods to Be and LiH and found that significant improvements in the accuracy of the approach are achieved if multi-configuration wave functions are used in preference to self-consistent field wave functions.
18 Nov 1985
TL;DR: In this paper, two basic static and dynamic computation assignment schemes are proposed for assigning the primary estimate computations (PECs) to processors in a parallel computer, which can be used to design parallel Monte Carlo algorithms for many applications.
Abstract: This paper demonstrates that the potential of intrinsic parallelism in Monte Carlo methods, which has remained essentially untapped so far, can be exploited to implement these methods efficiently on SIMD and MIMD computers. Two basic static and dynamic computation assignment schemes are proposed for assigning the primary estimate computations (PECs) to processors in a parallel computer. These schemes can be used to design parallel Monte Carlo algorithms for many applications. The time complexity analyses of static computation assignment (SCA) schemes are carried out using some results from order statistics, whereas those of dynamic computation assignment (DCA) schemes are carried out using results from order statistics, renewal and queueing theories. It is shown that for smaller number of processors, linear speedup can be achieved with the SCA schemes and the speedup almost equal to the number of processors can be achieved with the DCA schemes. Some computational results for Monte Carlo solutions of Lapla...
TL;DR: In this article, high-precision Monte Carlo data are used to estimate the exponents which govern the asymptotic behaviour of the recently introduced indefinitely growing self-avoiding walk in two dimensions.
Abstract: High-precision Monte Carlo data are used to estimate the exponents which govern the asymptotic behaviour of the recently introduced indefinitely-growing self-avoiding walk in two dimensions. For this walk the exponent gamma is by definition equal to one. Applying the same methods which are used to extract the exponents from exact series enumeration, the authors give an estimate for the exponent nu of 0.567+or-0.003. The leading corrections to this asymptotic behaviour are also calculated.
TL;DR: Monte Carlo simulations are performed for the spin-\textonehalf{} $\mathrm{XY}$ model in two dimensions for large lattices and the specific heat per spin approaches a finite value and does not diverge.
Abstract: Monte Carlo simulations are performed for the spin-\textonehalf{} $\mathrm{XY}$ model in two dimensions for large (up to 24\ifmmode\times\else\texttimes\fi{}24 sites) lattices. Results are obtained over a wide temperature range which includes the critical temperature ${T}_{c}$, estimated to be 0.4-0.5. The energy, specific heat, vortex density, and derivative of the helicity modulus are given as functions of temperature. As the lattice size is increased, the specific heat per spin approaches a finite value and does not diverge.
01 Feb 1985-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, a special Monte Carlo algorithm (importance sampling random walk) was used for parameter estimation in cases where the least-squares method fails, which makes possible the evaluation of confidence limits in neutron dose problems.
Abstract: Bayes' formalism is applied to neutron dosimetry problems. It is shown that this formalism and a special Monte Carlo algorithm (importance sampling random walk) can be used for parameter estimation in cases where the least-squares method fails. Three examples are discussed. The essential advantages of this method are that it makes possible the evaluation of confidence limits in neutron dose problems and the determination of the (unfolded) neutron spectrum from a set of a few reaction rates.
TL;DR: In this paper, a Monte Carlo study of the 2D kinetic Ising model is described in terms of a simple exponential relaxation of the magnetisation which enables a reliable estimate of the dynamical critical exponent, z, to be made.
Abstract: This paper describes a Monte Carlo study of the 2D kinetic Ising model. The long-time behaviour of various time-delayed correlation functions is investigated by renormalisation group methods. This long-time behaviour can be described in terms of a simple exponential relaxation of the magnetisation which enables a reliable estimate of the dynamical critical exponent, z, to be made.
TL;DR: The machine is quite versatile, easy to operate, and executes programs written in a high level C language, with a very fast, dedicated Monte Carlo processor and a general purpose single‐board computer sharing the 16‐Mbyte address space.
Abstract: Design, hardware, and operating software of a special purpose computer built for the Monte Carlo simulations of a wide class of random Ising spin systems is described. The machine is quite versatile, easy to operate, and executes programs written in a high level C language. It is a 32‐bit bus oriented system, with a very fast, dedicated Monte Carlo processor and a general purpose single‐board computer sharing the 16‐Mbyte address space. The former processor executes the basic Monte Carlo heat bath algorithm, and the latter performs required physical ‘‘measurements’’ on spin configurations and handles communication with a UNIX host machine. The host computer is used to compile and download programs and to receive small quantities of reduced data for permanent storage and further analysis.
TL;DR: In this article, a statistical model for the multifragmentation of finite excited nuclei is proposed, and the representation of the partition space in a Monte Carlo calculation is discussed, and it is shown that the most probable partitions are not necessarily the most dominant experimental ones.
TL;DR: In this article, an arbitrary-collision sampling technique for Monte Carlo calculations of the diffusion term in the density gradient expanded energy distribution functions is presented. But the technique is not suitable for the case of electron swarm transport in the ramp model gas and CH4.
Abstract: The authors have developed an arbitrary-collision sampling technique for Monte Carlo calculations of the diffusion term in the density gradient expanded energy distribution functions. The technique is shown to provide for an alternative and accurate Monte Carlo calculation of the diffusion coefficients. Comparisons of the diffusion distribution function for the cases of electron swarm transport in the ramp model gas and CH4 show excellent agreement with the results obtained by the Boltzmann method of Pitchford and Phelps (1982). However, there remains a discrepancy for the case of N2.