On calculations of correlated wave functions with heavy configurational mixing

Nicolaides, CA

dc.contributor.author	Nicolaides, CA	en
dc.date.accessioned	2014-03-01T01:22:51Z
dc.date.available	2014-03-01T01:22:51Z
dc.date.issued	2005	en
dc.identifier.issn	0020-7608	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/16684
dc.subject	Hole states	en
dc.subject	Multiple electron correlation	en
dc.subject.classification	Chemistry, Physical	en
dc.subject.classification	Mathematics, Interdisciplinary Applications	en
dc.subject.classification	Physics, Atomic, Molecular & Chemical	en
dc.subject.other	Approximation theory	en
dc.subject.other	Computational methods	en
dc.subject.other	Continuum mechanics	en
dc.subject.other	Correlation methods	en
dc.subject.other	Electronic structure	en
dc.subject.other	Functions	en
dc.subject.other	Hamiltonians	en
dc.subject.other	Mathematical models	en
dc.subject.other	Hole states	en
dc.subject.other	Multiple electron correlation	en
dc.subject.other	Orbitals	en
dc.subject.other	Wave functions	en
dc.subject.other	Quantum theory	en
dc.title	On calculations of correlated wave functions with heavy configurational mixing	en
heal.type	journalArticle	en
heal.identifier.primary	10.1002/qua.20390	en
heal.identifier.secondary	http://dx.doi.org/10.1002/qua.20390	en
heal.language	English	en
heal.publicationDate	2005	en
heal.abstract	We discuss aspects of the theory and computation of wave functions and energies of discrete states of polyelectronic atoms that are represented in zero order by configurations with holes in subshells below the valence subshell. Both in zero order and in the remaining correlation components, such wave functions have particularities stemming from the state-specific self-consistent field and the heavy configurational mixing associated with near-degeneracies and hole-filling correlations. By referring to a variety of examples from small- and large-scale calculations, it is noted that appropriate penetration into the many-body problem can provide, in an economic and physically transparent way, reliable interpretations and semi- and fully quantitative understanding of issues related to states with inner holes and to cases of near-degeneracies that result in strongly correlated wave functions. Whenever hole-filling correlations are allowed, multiple correlations (i.e., beyond single- and double-orbital substitutions in the single reference configuration) acquire increased importance relative to that in ordinary electronic structures. This is demonstrated via large-scale multiconfigurational Hartree-Fock (MCHF) plus configuration interaction (0) calculations on the Cl KL3s3p(6) IS discrete state, which is the lowest of its symmetry. The calculations incorporated correlations up to selected sextuple orbital excitations from the M shell. MCHF plus Cl calculations at the level of quadruple orbital substitutions were also carried out for the Cl KL3s(2)3p(5) P-2 degrees ground state and the excitation energy at this level of calculation was found to be 85,364 cm(-1), in excellent agreement with the experimental value of the finestructure-weighted average, 85,385 cm(-1) (10.59 eV). Within the approximations of the calculation, the hole-filling triple and quadruple orbital correlations, which, of course, are absent from the P-2 degrees state, contribute about 1 eV, which is significant. (c) 2004 Wiley Periodicals, Inc.	en
heal.publisher	JOHN WILEY & SONS INC	en
heal.journalName	International Journal of Quantum Chemistry	en
dc.identifier.doi	10.1002/qua.20390	en
dc.identifier.isi	ISI:000231913500002	en
dc.identifier.volume	102	en
dc.identifier.issue	3	en
dc.identifier.spage	250	en
dc.identifier.epage	264	en