Search results for " Convergence"

Direct perturbation theory in terms of energy derivatives: scalar-relativistic treatment up to sixth order.

2011

A formulation of sixth-order direct perturbation theory (DPT) to treat relativistic effects in quantum-chemical calculations is presented in the framework of derivative theory. Detailed expressions for DPT6 are given at the Hartree-Fock level in terms of the third derivative of the energy with respect to the relativistic perturbation parameter defined as λ(rel)=c(-2). They were implemented for the computation of scalar-relativistic energy corrections. The convergence of the scalar-relativistic DPT expansion is studied for energies and first-order properties such as dipole moment and electric-field gradient within the series of the hydrogen halides (HX, X = F, Cl, Br, I, and At). Comparison …

Boundary regularity and the uniform convergence of quasiconformal mappings

1979

A new result on impulsive differential equations involving non-absolutely convergent integrals

2009

AbstractIn this paper we obtain, as an application of a Darbo-type theorem, global solutions for differential equations with impulse effects, under the assumption that the function on the right-hand side is integrable in the Henstock sense. We thus generalize several previously given results in literature, for ordinary or impulsive equations.

Some supplementary results on the 1+ $$\sqrt 2 $$ order method for the solution of nonlinear equations

1982

Recently an iterative method for the solution of systems of nonlinear equations having at leastR-order 1+ $$\sqrt 2 $$ for simple roots has been investigated by the author [7]; this method uses as many function evaluations per step as the classical Newton method. In the present note we deal with several properties of the method such as monotone convergence, asymptotic inclusion of the solution and convergence in the case of multiple roots.

La convergence des systèmes nationaux de gouvernance: une perspective contingente

2009

The objective of this paper is to show that the answer to the question of convergence of national systems of governance is contingent on a number of assumptions. The first assumption bears on the functions and the formal mechanisms characterizing the systems of governance. The second concerns the possibility to define a unique national system of governance for all the firms of a nation. The third focuses on the process of homogenization of national systems of governance attributed to globalization.

Total Factor Productivity Convergence Amongst Italian Regions: Some Evidence from Panel Unit Root Tests

2009

Byrne J. P., Fazio G. and Piacentino D. Total factor productivity convergence among Italian regions: some evidence from panel unit root tests. Regional Studies. This paper employs panel unit root tests to investigate convergence in total factor productivity (TFP) among Italian regions. These tests provide an inference valid in the presence of heterogeneity and cross-sectional dependence, and when the cross-sectional dimension is smaller than the time dimension, allowing the investigation of convergence among different subsets of regions. The results add a further dimension to the conventional view on growth dynamics in the Italian peninsula depicting a lack of regional TFP convergence not o…

Size-intensive decomposition of orbital energy denominators

2000

We introduce an alternative to Almlöf and Häser’s Laplace transform decomposition of orbital energy denominators used in obtaining reduced scaling algorithms in perturbation theory based methods. The new decomposition is based on the Cholesky decomposition of positive semidefinite matrices. We show that orbital denominators have a particular short and size-intensive Cholesky decomposition. The main advantage in using the Cholesky decomposition, besides the shorter expansion, is the systematic improvement of the results without the penalties encountered in the Laplace transform decomposition when changing the number of integration points in order to control the convergence. Applications will…

Weak convergence to the coalescent in neutral population models

1999

For a large class of neutral population models the asymptotics of the ancestral structure of a sample of n individuals (or genes) is studied, if the total population size becomes large. Under certain conditions and under a well-known time-scaling, which can be expressed in terms of the coalescence probabilities, weak convergence in D E ([0,∞)) to the coalescent holds. Further the convergence behaviour of the jump chain of the ancestral process is studied. The results are used to approximate probabilities which are of certain interest in applications, for example hitting probabilities.

A Nonlinear Primal-Dual Method for Total Variation-Based Image Restoration

1999

We present a new method for solving total variation (TV) minimization problems in image restoration. The main idea is to remove some of the singularity caused by the nondifferentiability of the quantity $|\nabla u|$ in the definition of the TV-norm before we apply a linearization technique such as Newton's method. This is accomplished by introducing an additional variable for the flux quantity appearing in the gradient of the objective function, which can be interpreted as the normal vector to the level sets of the image u. Our method can be viewed as a primal-dual method as proposed by Conn and Overton [ A Primal-Dual Interior Point Method for Minimizing a Sum of Euclidean Norms, preprint,…

Neoclassical growth, manufacturing agglomeration, and terms of trade

2007

This paper presents an integrated view of economic growth, development traps, and economic geography. We explain why there is income convergence among some countries (neoclassical regime) and income divergence among others (poverty trap regime). Income convergence (divergence) and manufacturing industry diffusion (agglomeration) are re-enforcing each other in a cumulative process. Moreover, trade openness may trigger a catch-up process of an economy that is stuck in a \"poverty trap\". This catch-up is characterized by an increase in the investment-to-GDP ratio and an improvement of the terms of trade. A new dynamic welfare gain of trade liberalization is identified, which is likely to be l…