9 research outputs found
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