Abstract The problem of atomic ionization by the sudden absorption momentum its nucleus is studied. By means a simple one dimensional model we obtain analytical expression for re-capture and probabilities. Simple integral formulas evaluation time evolution electronic state are given. Analytical expressions ionisation probabilities show structures found in realistic three collisional problems, such as capture probability (by recoil nucleus) binary peak.

In this paper we discuss the optimization of Sturmian basis functions by studying bound atomic systems within configuration interaction method. Our investigation clearly shows how fulfillment correct physical boundary conditions at short and large distances from nucleus improves convergence rate This is illustrated first through a one-electron atom, then with two-electron systems. For ground state helium 35 per electron angular momenta, obtain an energy $\ensuremath{-}2.903 712 820$ a.u.,...

We describe astra (attosecond transitions), a close-coupling approach to molecular ionization that uses many-body transition-density matrices between ionic states with arbitrary spin and symmetry, in combination hybrid integrals Gaussian numerical orbitals, efficiently evaluate photoionization observables. Within the transition-density-matrix approach, evaluation of interchannel coupling is exact does not depend on size configuration-interaction space ions. Thanks these two crucial features,...

We present a spectral method to study three-body fragmentation processes. The basis set explicitly includes continuum asymptotic boundary conditions, and it is built upon generalized Sturmian functions. These functions are eigenvectors of two-body problem where the magnitude potential assumed as eigenvalue. Comparison with simple solvable analytical model demonstrates that our approach rapidly converges exact results, sizes much smaller than other previous calculations. Preliminary...

The properties of a helium atom confined inside an endohedral cavity, such as fullerene, are studied. fullerene cavity is modeled by potential well and the strength this varied in order to understand collapse different atomic wave functions into cage. Three theoretical calculation methods have been developed: relaxation method, Sturmian basis variational method. first two nonperturbative. three allow inclusion full correlations among electrons. Results showing mirror effects presented for...

In this paper the double ionization of helium by high-energy electron impact is studied. The corresponding four-body Schr\"odinger equation transformed into a set driven equations containing successive orders in projectile-target interaction. transition amplitude obtained from asymptotic limit first-order solution shown to be equivalent familiar first Born approximation. solved within generalized Sturmian approach for an $S$-wave $(e,3e)$ model process with high incident energy and small...

An analytically solvable three-body collision system ($s$ wave) model is used to test two different theoretical methods. The first one a configuration interaction expansion of the scattering wave function using basis set Generalized Sturmian Functions (GSF) with purely outgoing flux (CISF), introduced recently in A. L. Frapicinni, J. M. Randazzo, G. Gasaneo, and F. D. Colavecchia [J. Phys. B: At. Mol. Opt. 43, 101001 (2010)]. second finite element method (FEM) calculation performed...

We present a configuration-interaction (CI) method based on Sturmian functions. The components of this CI basis are the solutions two-body eigenproblem, where eigenvalues related to interacting potential in equation. Our accommodates any arbitrary, physically sound, central equations and different adequate asymptotic conditions. Computation eigenfunctions is performed by direct numerical discretization apply obtain bound states for two-electron systems. show convergence partial-wave...

In this paper we present a theory to describe three-body reactions. Fragmentation processes are studied by means of the Schrödinger equation in hyperspherical coordinates. The wave function is written as sum two terms. first one defines initial channel collision while second describes scattered wave, which contains all information about process. dynamics ruled an nonhomogeneous with driven term related and interactions. A basis set functions outgoing behavior at large values hyperradius...

Abstract In this work, we present a method to obtain two‐particle Coulomb Sturmians Functions (CSF) with an expansion in set of L 2 basis functions. the two‐body case, recover exact (discrete) spectrum CSFs for negative energies and discretized approximation positive ones. Besides, make use analyze two‐independent electron problem as Generalized Sturmian problem. We propose version wave function terms CSF states, show that reduces find numerical coincidences between energy‐dependent...

We present a configuration interaction (CI) method based on the Sturmian expansion for bound states of two-electron atomic system. These functions are solutions one-electron quantum mechanical problems, where eigenvalue is magnitude short-range potential. Also, they fulfill long-range boundary conditions Coulomb potentials. choose to expand Sturmians CI basis using ${L}^{2}$ Laguerre-type functions. compute ground and single-excited energies He ${\mathrm{H}}^{\ensuremath{-}}$. Moreover, we...

The photodouble ionization of the water molecule is studied at 20 eV excess energy in a combined experimental and theoretical investigation. In experiments, two photoelectrons equal kinetic are detected coincidence after angular selection. On side, generalized Sturmian function approach implemented to describe accurately correlated two-electron continuum, while separable products Moccia orbitals [J. Chem. Phys. 40, 2164 (1964)] used for initial electronic state molecule. triple-differential...

Abstract In this work we introduce a method to construct Sturmian functions for general interaction potentials in two‐body problems. We expand these Sturmians on finite L 2 space, using N Laguerre basis obtain discrete set of eigenvalues positive and negative energies. Orthogonality closure relations are thus rewritten expansions; completeness is achieved through increasing the size. apply Coulomb Herman Skillman potential. study behavior obtained their convergence an overall range The...

Abstract The ground state energy of a helium atom inside spherical multilayer quantum dot as function the atomic impurity location has been calculated. is modeled by core/shell/well/shell structure using parabolic confinement. Configuration Interaction method and Diffusion Monte Carlo have used to solve Schrödinger equation. Results obtained showed that lowest configuration depends on size different layers agreement between results indicates approach here would be suitable compute excited...

Abstract In this article, we investigate discretization schemes to represent Sturmian functions for both positive and negative energies in the presence of a long range Coulomb potential. We explore two methods obtain energy. The first one involves expansion radial wave function L 2 finite basis set, whereas second introduces coordinate domain Hamiltonian or, alternatively, Green function. apply them find bound states scattering phase shift ${\cal N}$ ‐electron atoms close critical charge....

We compare the physical information contained in Temkin-Poet (TP) scattering wave function representing electron-impact ionization of hydrogen, calculated by convergent close-coupling (CCC) and generalized Sturmian (GSF) methodologies. The idea is to show that cross section can be extracted from functions themselves. Using two different procedures based on hyperspherical we transition amplitudes both GSF CCC lead similar single-differential sections. single-continuum channels were also a...

In this study, we address the problem of a C60 endohedrally confined hydrogen molecule through configuration-interaction approach to electronic dynamics. Modeling confinement by means combination two Woods-Saxon potentials, analyze stability system as function nuclei position behavior spectrum. After studying convergence different partial wave expansions, one related molecular Coulomb centers and other off-centering well, found that second provides more accurate description system....

In this work, we propose a novel asymmetric isochronous pendulum, where half of the trajectory corresponds to that (non-isochronous) simple while remaining part specific trajectory. The pendulum's complete swing is isochronous—i.e., its period not dependent on oscillation amplitude. This new design inspired by symmetric Huygens in which modified cycloidal guides. our case, only one guide needed, for analytical expressions are given first time. objective paper add pedagogical tool...

Abstract The photodouble ionization of water at about 32 eV excess energy has been investigated both experimentally and theoretically. In an angular resolved photoelectron–photoelectron coincidence experiment, the two photoelectrons in unequal sharing (25 7 eV) condition, have detected a plane perpendicular to propagation direction linearly polarized radiation. measured distributions compared with, molecular orientation averaged, triple differential cross sections calculated with recently...

Fil: Lopez, Sebastian David. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina Coordinacion Administrativa Ciudad Universitaria. Instituto Astronomia Fisica del Espacio. - Universidad Buenos Aires. Facultad Ciencias Exactas Naturales. Espacio; Argentina

The potential energy interaction between a system of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mi>N</mml:mi> </mml:math> -charged particles and spherical conducting surface is obtained by means direct integration the electrostatic density. Making use image charge method, we show that full can be split into sum one-body central potentials two-body contributions related to particle–particle particle–sphere interactions. Analytical...

We theoretically study atomic laser-assisted photoelectric emission (LAPE) beyond the electric dipole approximation. present a theoretical description for first-order nondipole corrections ($O(c^{-1})$ where $c$ is speed of light) to nonrelativistic laser-atom interaction strong circularly polarized infrared (IR) laser field combined with train extreme-ultraviolet (XUV) pulses. investigate photoelectron momentum distribution (PMD) as product two main contributions: intra- and interpulse...