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Linear Scaling Electronic Structure Methods with Periodic Boundary Conditions

Description: The methodological development and computational implementation of linear scaling quantum chemistry methods for the accurate calculation of electronic structure and properties of periodic systems (solids, surfaces, and polymers) and their application to chemical problems of DOE relevance.
Date: February 8, 2008
Creator: Scuseria, Gustavo E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Improved resonance reaction rate calculation for lattice physics subsystem

Description: The resonance capture calculations of the HAMMER System and HAMBUR System are derived from a consistent statement of the integral slowing down equation and definitions of the resonance integral. The assumptions made in these treatments are explicitly stated, and and an attempt is made to estimate the possible error in the resonance integral arising from these assumptions. This analysis is made to pin-point those parts of the calculation that can be improved and updated. Based on the analysis of… more
Date: February 8, 1974
Creator: Finch, D.R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Exact calculations of phase and membrane equilibria for complex fluids by Monte Carlo simulation

Description: Objective is to develop molecular simulation techniques for phase equilibria in complex systems. The Gibbs ensemble Monte Carlo method was extended to obtain phase diagrams for highly asymmetric and ionic fluids. The modified Widom test particle technique was developed for chemical potentials of long polymeric molecules, and preliminary calculations of phase behavior of simple model homopolymers were performed.
Date: June 8, 1992
Creator: Panagiotopoulos, A.Z.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Formulation of the Linear Response Theory in Relativistic LAPW Method. Calculation of Forces in Alpha-Pu

Description: Linear-response (LR) theory in combination with the first-principles band structure codes allows to calculate phonons in an efficient way. In this report a formalism which enables us to apply LR theory within an all-electron framework utilizing the relativistic full-potential linearized augmented plane-wave (RFLAPW) method is presented. As first part, the equations for the calculations of the atomic forces are given and they are used for the calculation of forces in {alpha}-Pu. As a second step… more
Date: January 8, 2004
Creator: Kutepov, A L
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Application of automatic differentiation for the simulation of nonisothermal, multiphase flow in geothermal reservoirs

Description: Simulation of nonisothermal, multiphase flow through fractured geothermal reservoirs involves the solution of a system of strongly nonlinear algebraic equations. The Newton-Raphson method used to solve such a nonlinear system of equations requires the evaluation of a Jacobian matrix. In this paper we discuss automatic differentiation (AD) as a method for analytically computing the Jacobian matrix of derivatives. Robustness and efficiency of the AD-generated derivative codes are compared with a … more
Date: January 8, 2002
Creator: Kim, Jong G. & Finsterle, Stefan
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Logistic Regression Applied to Seismic Discrimination

Description: The usefulness of logistic discrimination was examined in an effort to learn how it performs in a regional seismic setting. Logistic discrimination provides an easily understood method, works with user-defined models and few assumptions about the population distributions, and handles both continuous and discrete data. Seismic event measurements from a data set compiled by Los Alamos National Laboratory (LANL) of Chinese events recorded at station WMQ were used in this demonstration study. PNNL … more
Date: October 8, 1998
Creator: Amindan, BG & Hagedorn, DN
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Preliminary Evaluation of Techniques to Fabricate Beryllium, Polyimide, and Ge-doped CH/CD Ablator Materials

Description: This report including appendices provides information to complete this deliverable. It summarizes the important features of each ablator material, with particular focus to its usefulness for ignition capsules. More detailed discussions of each ablator type are in the Appendix. Included at the end of each separate discussion in the Appendix is a list of all published work with an ICF focus on that ablator type. This report is organized into Be based and polymer (C) based ablators. We summarize s… more
Date: November 8, 2004
Creator: Cook, Bob; Letts, Steve; Nikroo, Abbas; Nobile, Art; McElfresh, Mike; Cooley, Jason et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Composite centered schemes for multidimensional conservation laws

Description: The oscillations of a centered second order finite difference scheme and the excessive diffusion of a first order centered scheme can be overcome by global composition of the two, that is by performing cycles consisting of several time steps of the second order method followed by one step of the diffusive method. The authors show the effectiveness of this approach on some test problems in two and three dimensions.
Date: May 8, 1998
Creator: Liska, R. & Wendroff, B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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WUFI-ORNL/IBP Hygrothermal Model

Description: Moisture engineering is becoming an important task in the overall design of building enclosures in both North America and Europe. Several methods may be used to design wall systems, and modeling is definitively the most flexible approach. There is an increasing demand for calculation methods to assess the moisture behavior of building components. In North America alone, the estimated cost in increased energy consumption due to the presence of moisture is approximately $1 billion dollars annuall… more
Date: August 8, 2001
Creator: Karagiozis, A.N.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The effect of dividing the magnets on the calculation of the recycler dynamic aperture

Description: The modeling of a lattice and the calculation of the dynamic aperture, are exercises fraught with uncertainty and possible error. If we want an accurate value for the dynamic aperture, we must start with an accurate model for the lattice. This model should incorporate the misalignments, including the rolls, of the lattice elements, as well as the error fields in the magnets. These quantities are not always well known. It has been known for sometime that long term tracking must be symplectic. Th… more
Date: May 8, 2001
Creator: Gelfand, Norman
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Dyson-Schwinger equations: connecting small and large length-scales.

Description: The phenomenological application of Dyson-Schwinger equations to the calculation of meson properties observable at TJNAF is illustrated. Particular emphasis is given to the ability of this framework to unify long-range effects constrained by chiral symmetry with short-range effects prescribed by perturbation theory, and interpolate between them.
Date: February 8, 1999
Creator: Roberts, C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Four-button BPM coefficients in cylindrical and elliptic beam chambers.

Description: Beam position monitor (BPM) coefficients are calculated from induced charges on four-button BPMs in circular and elliptic beam chambers for {gamma} >>1. Since the beam chamber cross-section for the APS storage ring is different from an exact elliptic geometry, numerical values of the BPM coefficients and their inversions are computed from two-dimensional electrostatic field distributions inside an exact geometry of the beam chamber. Utilizing Green's reciprocation theorem, a potential val… more
Date: April 8, 1999
Creator: Kim, S. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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