Energetics of [Fe(NCH)6]2+ via CASPT2 calculations : a spin-crossover perspective
2009 Wiley Periodicals, Inc.
| Publié dans: | Journal of computational chemistry. - 1984. - 30(2009), 14 vom: 15. Nov., Seite 2327-33 |
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| Auteur principal: | |
| Autres auteurs: | , , |
| Format: | Article en ligne |
| Langue: | English |
| Publié: |
2009
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| Accès à la collection: | Journal of computational chemistry |
| Sujets: | Journal Article Ferrous Compounds |
| Résumé: | 2009 Wiley Periodicals, Inc. The importance of basis sets and active spaces in the determination of the potential energy curves and relevant energy differences in the O(h)-symmetry model system [Fe(NCH)(6)](2+) is analyzed using the Complete Active Space Self-Consistent Field (CASSCF) method and subsequent second-order perturbative treatment (CASPT2). By comparison of a series of atomic basis sets contraction, it is concluded that a balanced description of the Fe 7s6p5d3f2g1h and N 4s3p1d partners is needed to reach convergence upon the potential energy surface descriptions. Since the spin-crossover phenomenon involves the simultaneous change in the spin nature and expansion of the coordination sphere of the metal ion (i.e., lengthening of the Fe-N distances), the standard 10 electrons/12 orbitals complete active space is confronted to a chemically intuitive 18 electrons/15 orbitals picture. The role of a second d-shell is finally examined using the extended RAS strategy. Using a valence-bond type analysis, it is shown that the so-called d(') orbitals allow for a significant charge redistribution (approximately 0.5 electron) along the transition. Our calculations are compared to reference coupled-cluster estimations |
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| Description: | Date Completed 19.01.2010 Date Revised 31.08.2009 published: Print Citation Status MEDLINE |
| ISSN: | 1096-987X |
| DOI: | 10.1002/jcc.21236 |