dc.contributor.author |
Koch, W |
|
dc.contributor.author |
Frey, B |
|
dc.contributor.author |
Ruiz, JFS |
|
dc.contributor.author |
Scior, T |
|
dc.date.accessioned |
2011-01-22T10:26:41Z |
|
dc.date.available |
2011-01-22T10:26:41Z |
|
dc.date.issued |
2003 |
|
dc.identifier.issn |
0932-0784 |
|
dc.identifier.uri |
http://hdl.handle.net/11154/1622 |
|
dc.description.abstract |
Rudenberg's well-known letter of 1951 entitled "On the Three- and Four-Center Integrals in Molecular Quantum Mechanics" explicitly presents two approximation formulas for four-center repulsion integrals, only. When applied to some types of three-center repulsion integrals, however, these two recipes still imply considerable oversimplifications. Using both one-electron and two-electron routes of Rudenberg's truncated expansion, on the other hand, such shortcomings can be avoided strictly. Starting from four simple "Unrestricted and Combined" (U&C) approximation schemes introduced elsewhere, an improved "Restricted and Combined" (R&C) approximation picture for Fock-matrix elements now will be outlined, which does not tolerate any unnecessary oversimplifications. Although the simplicity of the U&C scheme is lost in this case, R&C-approximated Fock-matrix elements still can be constructed from one- and two-center integrals alone in an effective way. Moreover, due to their dependence on a single geometric parameter, all types of two-center integrals can be calculated in advance for about one hundred fixed interatomic distances at the desired level of sophistication and stored once and for all. A cubic spline algorithm may be taken to interpolate the actual integral value from each precomputed list. |
en_US |
dc.language.iso |
en |
en_US |
dc.title |
On the restricted and combined use of Rudenberg's approximations in molecular orbital theories of Hartree-Fock type |
en_US |
dc.type |
Article |
en_US |
dc.identifier.idprometeo |
1852 |
|
dc.source.novolpages |
58(12):756-784 |
|
dc.subject.wos |
Chemistry, Physical |
|
dc.subject.wos |
Physics, Multidisciplinary |
|
dc.description.index |
WoS: SCI, SSCI o AHCI |
|
dc.subject.keywords |
unrestricted (and restricted) Hartree-Fock molecular orbitals |
|
dc.subject.keywords |
integral approximations according to Mulliken and Rudenberg |
|
dc.subject.keywords |
Zero Differential Overlap (ZDO) |
|
dc.subject.keywords |
Neglect of Diatomic Differential Overlap (NDDO) |
|
dc.subject.keywords |
Extended Huckel Theory (EHT) |
|
dc.relation.journal |
Zeitschrift Fur Naturforschung Section A-A Journal of Physical Sciences |
|