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Publications

New algebraic formulation of density functional calculation

Cornell Affiliated Author(s)
Author
S. Ismail-Beigi
Tomas Arias
Abstract

This article addresses a fundamental problem faced by the community employing single-particle ab initio methods: the lack of an effective formalism for the rapid exploration and exchange of new methods. To rectify this, we introduce a new, basis-set independent, matrix-based formulation of generalized density functional theories which reduces the development, implementation, and dissemination of new techniques to the derivation and transcription of a few lines of algebra.

Journal
Computer Physics Communications
Date Published
Funding Source
338297
347887
DMR-9632275
DMR 94-00334
9632275
BR-3456
Group (Lab)
Tomas Arias Group

Chemical reactions and phase equilibria of model halocarbons and salts in sub- and supercritical water (200-300 bar, 100-600°C)

Cornell Affiliated Author(s)
Author
J.W. Tester
P. Marrone
M.M. DiPippo
K. Sako
M.T. Reagan
Tomas Arias
W.A. Peters
Abstract

Experimental data and theoretical predictions of hydrolysis reaction kinetics of model halocarbons and phase equilibria of their associated neutralized salt reaction products are reported for a range of hydrothermal conditions. Specifically, the results of a study of hydrolysis and oxidation of methylene chloride (CH2Cl2) to produce CO2, H2O, and HCl as final mineralized products are presented.

Journal
Journal of Supercritical Fluids
Date Published
Funding Source
DMR94-00334
DAAG04-94-G-0145
DAAH04-96-1-0174
DAAL03-92-G-0177-URI
BR-3456
Group (Lab)
Tomas Arias Group

Multiscale Computation with Interpolating Wavelets

Cornell Affiliated Author(s)
Author
R.A. Lippert
Tomas Arias
A. Edelman
Abstract

Multiresolution analyses based upon interpolets, interpolating scaling functions introduced by Deslauriers and Dubuc, are particularly well-suited to physical applications because they allowexactrecovery of the multiresolution representation of a function from its sample values on afiniteset of points in space. We present a detailed study of the application of wavelet concepts to physical problems expressed in such bases.

Journal
Journal of Computational Physics
Date Published
Funding Source
9404326-CCR
DMR 94-00334
BR-3456
9404326
Group (Lab)
Tomas Arias Group

The geometry of algorithms with orthogonality constraints

Cornell Affiliated Author(s)
Author
A. Edelman
Tomas Arias
S.T. Smith
Abstract

In this paper we develop new Newton and conjugate gradient algorithms on the Grassmann and Stiefel manifolds. These manifolds represent the constraints that arise in such areas as the symmetric eigenvalue problem, nonlinear eigenvalue problems, electronic structures computations, and signal processing. In addition to the new algorithms, we show how the geometrical framework gives penetrating new insights allowing us to create, understand, and compare algorithms.

Journal
SIAM Journal on Matrix Analysis and Applications
Date Published
Group (Lab)
Tomas Arias Group

Linking computational methods across different length scales

Cornell Affiliated Author(s)
Author
V.V. Bulatov
S. Yip
Tomas Arias
Abstract

Throughout the Plenary and Break-Out Sessions at the Workshop the issue was frequently brought up of linking together computational approaches which traditionally operate on distinct length scales. In response to this interest, an informal discussion was held to examine the prospects for a collaborative initiative on coupling atomistic and continuum methods.

Journal
Journal of Computer-Aided Materials Design
Date Published
Group (Lab)
Tomas Arias Group