uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
1994 (English)In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 27, no 6, 1061-1072 p.Article in journal (Refereed) Published
Abstract [en]

In studies of hydrogenic systems via the recursive residue generation method (RRGM) the major bottleneck is the matrix vector product HC, between the Hamiltonian matrix H and a Lanczos vector C. For highly excited states and/or strong perturbations the size of H grows fast leading to storage problems. By making-use of direct methods, i.e. avoidance of explicit construction on of large Hamiltonian matrices, such problems can be overcome. Utilizing the underlying analytical properties of the Laguerre basis e(-lambdar)L(k)2I+2(2lambdar) a direct RRGM (D-RRGM) for the unperturbed hydrogenic Hamiltonian is derived, changing the storage needs from scaling as N2 to 4N where N is the number of radial functions for each factorized H-0(l, m) block with the possibility of parallel processing. A further computational simplification is introduced by putting the expression for the photoionization (PI) cross section in the rational form conventionally used in the representation of density or states (DOS). This allows the construction of the PI cross section directly from the tridiagonal Lanczos matrix avoiding the explicit calculation of individual eigenvalues and eigenvectors. To illustrate and verify the method the PI cross section for a hydrogen atom in a static electric field, for both pi and cr polarization, was calculated for an electric field strength of F = 5714 V cm-1. Sufficiently large basis sets could be employed so that good comparison with experiment and other theoretical work was obtained, including the field-induced modulations near the zero-field ionization limit.

Place, publisher, year, edition, pages
1994. Vol. 27, no 6, 1061-1072 p.
URN: urn:nbn:se:uu:diva-144175ISI: A1994ND74900007OAI: oai:DiVA.org:uu-144175DiVA: diva2:392729
Available from: 2011-01-27 Created: 2011-01-27 Last updated: 2011-01-27

Open Access in DiVA

No full text

Search in DiVA

By author/editor
In the same journal
Journal of Physics B: Atomic, Molecular and Optical Physics

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 389 hits
ReferencesLink to record
Permanent link

Direct link