Degrees of validity of models for the description of doubly excited states of H- and He

Nicolaides, CA; Themelis, SI; Komninos, Y

dc.contributor.author	Nicolaides, CA	en
dc.contributor.author	Themelis, SI	en
dc.contributor.author	Komninos, Y	en
dc.date.accessioned	2014-03-01T01:17:41Z
dc.date.available	2014-03-01T01:17:41Z
dc.date.issued	2002	en
dc.identifier.issn	0953-4075	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/14617
dc.subject.classification	Optics	en
dc.subject.classification	Physics, Atomic, Molecular & Chemical	en
dc.subject.other	Approximation theory	en
dc.subject.other	Electron resonance	en
dc.subject.other	Electronic density of states	en
dc.subject.other	Electronic structure	en
dc.subject.other	Hamiltonians	en
dc.subject.other	Helium	en
dc.subject.other	Hydrogen	en
dc.subject.other	Mathematical models	en
dc.subject.other	Probability	en
dc.subject.other	Quantum theory	en
dc.subject.other	Spectrum analysis	en
dc.subject.other	Doubly excited states (DES)	en
dc.subject.other	Electron energy levels	en
dc.title	Degrees of validity of models for the description of doubly excited states of H- and He	en
heal.type	journalArticle	en
heal.identifier.primary	10.1088/0953-4075/35/8/303	en
heal.identifier.secondary	http://dx.doi.org/10.1088/0953-4075/35/8/303	en
heal.language	English	en
heal.publicationDate	2002	en
heal.abstract	There are models for the description of doubly excited states (DES) of H- and He whose degrees of validity can be tested by comparing their results to those from theory based on the solution of the Schrodinger equation with the full Hamiltonian. Such comparisons are meaningful and definitive when a reasonably wide range of data are available. We present results for the energies and the nature of the wavefunctions of the four lowest P-1(0) DES of H- and of He for each hydrogenic manifold from N = 6 up to 25. These are used to establish the degree and range of validity of the quantum number n(2) introduced by Herrick and Kellman (Herrick D R and Kellman M E 1980 Phys. Rev. A 21 418) in their triatomic model for qualitative description of the spectra of DES, as well as of two classification schemes, as a function of level of excitation and of type of state. According to the model, the number 112 is equal to the number of nodes of the density P(theta(12)) of the corresponding DES. We present results of calculations Of P(theta(12)) using correlated wavefunctions for the four lowest states in the N = 10 and 25 manifolds. These show for the first time for such highly excited states how the angle opens as excitation increases. Furthermore, they indicate that n(2) provides a valid picture even up to N = 25. The first of the two classification schemes examined here is the (K, T) scheme, introduced by Herrick and Sinanoglu (Herrick D R and Sinanoklu 0 1975 Phys. Rev. A 11 97). It is shown quantitatively that it deteriorates as N increases and Z decreases. The second scheme is the (F, T) scheme, introduced by Komninos et al (Komninos Y, Themelis S, Chrysos M and Nicolaides C A 1993 Int. J. Quantum Chem. Suppl. 27 399), where F = N - K - 1 and N, K are not good numbers anymore. It is shown that it constitutes a consistently better representation, especially as the relative significance of electron correlation increases, as in the high-lying DES of H-. For the lowest intrashell and intershell states of each N-manifold, for which the calculation incorporates the effects of electron correlation to very high accuracy, the (F, T) 'purity' coefficient is very high, close to one.	en
heal.publisher	IOP PUBLISHING LTD	en
heal.journalName	Journal of Physics B: Atomic, Molecular and Optical Physics	en
dc.identifier.doi	10.1088/0953-4075/35/8/303	en
dc.identifier.isi	ISI:000175594800004	en
dc.identifier.volume	35	en
dc.identifier.issue	8	en
dc.identifier.spage	1831	en
dc.identifier.epage	1840	en