The calculation of indirect nuclear spin-spin coupling constants in large molecules
2004 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 10, no 18, 4627-4639 p.Article in journal (Refereed) Published
We present calculations of indirect nuclear spin-spin coupling constants in large molecular systems, performed using density functional theory. Such calculations, which have become possible because of the use of linear-scaling techniques in the evaluation of the Coulomb and exchange-correlation contributions to the electronic energy, allow us to study indirect spin-spin couplings in molecules of biological interest, without having to construct artificial model systems. In addition to presenting a statistical analysis of the large number of short-range coupling constants in large molecular systems, we analyse the asymptotic dependence of the indirect nuclear spin-spin coupling constants on the internuclear separation. In particular, we demonstrate that, in a sufficiently large one-electron basis set, the indirect spin-spin coupling constants become proportional to the inverse cube of the internuclear separation, even though the diamagnetic and paramagnetic spin-orbit contributions to the spin-spin coupling constants separately decay as the inverse square of this separation. By contrast, the triplet Fermi contact and spin-dipole contributions to the indirect spin-spin coupling constants decay exponentially and as the inverse cube of the internuclear separation, respectively. Thus, whereas short-range indirect spin-spin coupling constants are usually dominated by the Fermi contact contribution, long-range coupling constants are always dominated by the negative diamagnetic spin-orbit contribution and by the positive paramagnetic spin-orbit contribution, with small spin-dipole and negligible Fermi contact contributions.
Place, publisher, year, edition, pages
2004. Vol. 10, no 18, 4627-4639 p.
density functional calculations, NMR spectroscopy, response theory, spin-spin coupling constants, density-functional theory, linear scaling computation, ab-initio methods, magnetic-resonance, cluster calculations, orbital methods, wave-functions, fock matrix, basis-sets, electron
IdentifiersURN: urn:nbn:se:kth:diva-23768DOI: 10.1002/chem.200306065ISI: 000224146800027ScopusID: 2-s2.0-4744366709OAI: oai:DiVA.org:kth-23768DiVA: diva2:342467
QC 20100525 QC 201109162010-08-102010-08-102011-09-16Bibliographically approved