On the calculation of High-Spin states in the Full Configuration Interaction formalism

A modified electronic Hamiltonian that allows the calculations of high-spin eigenfunctions in the S_z=0 manifold, is presented. In this formalism the low-spin states are shifted in energy while all the states having a multiplicity larger than a given value are kept untouched. This formalism has been applied to a test calculations of the lowest quintet state of the helium dimer and of the quintet state of the Tetrahedral Li_4 Cluster

Blue satellites on He lines due to He-He collisions

The shape and broadening of He lines affects radiative transport in dense, He-rich, stellar atmospheres. At wavelengths inaccessible for direct observation, we rely on theoretical calculations of self-broadening to support stellar structure and spectral modeling. In this work, we examine lines of He due to 1s–2p and 2p–3s transitions. The line profiles are analyzed in terms of a unified theory of spectral line broadening using ab initio potential energies that have been recently determined. For temperatures up to 20 000 K, the linear dependence of width and shift on gas density and the non-linear dependence on temperature of the Lorentzian core of the resonance line are described. Beyond the conventional symmetrical Lorentzian core, we show that they are asymmetrical and have significant additional contributions on the short wavelength side. This blue asymmetry is a consequence of maxima in the corresponding He2 potential energy difference curves at short and intermediate internuclear distance. Over a limited range of density and temperature, laboratory measurements in the visible and near infrared can be used to validate the potentials that underlie the spectral line profile theory, which is useful for modeling spectra over the extreme ranges of temperature and density encountered in stellar and planetary atmospheres

Essai de typologie des symptomes de deperissement dans les massifs dauphinois externes (Vercors-Chartreuse-Belledonne)

CNRS RP 185 (2331) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Pour une approche interdisciplinaire de la qualité de l’emploi en Amérique latine

International audienc