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Embedding fragment ab initio model potentials in CASSCF/CASPT2 calculations of doped solids: Implementation and applications

Swerts, Ben; Chibotaru, Liviu F.; Lindh, Roland LU ; Seijo, Luis; Barandiaran, Zoila; Clima, Sergiu; Pierloot, Kristin and Hendrickx, Marc F. A. (2008) In Journal of Chemical Theory and Computation 4(4). p.586-594
Abstract
In this article, we present a fragment model potential approach for the description of the crystalline environment as an extension of the use of embedding ab initio model potentials (AIMPs). The biggest limitation of the embedding AIMP method is the spherical nature of its model potentials. This poses problems as soon as the method is applied to crystals containing strongly covalently bonded structures with highly nonspherical electron densities. The newly proposed method addresses this problem by keeping the full electron density as its model potential, thus allowing one to group sets of covalently bonded atoms into fragments. The implementation in the MOLCAS 7.0 quantum chemistry package of the new method, which we call the embedding... (More)
In this article, we present a fragment model potential approach for the description of the crystalline environment as an extension of the use of embedding ab initio model potentials (AIMPs). The biggest limitation of the embedding AIMP method is the spherical nature of its model potentials. This poses problems as soon as the method is applied to crystals containing strongly covalently bonded structures with highly nonspherical electron densities. The newly proposed method addresses this problem by keeping the full electron density as its model potential, thus allowing one to group sets of covalently bonded atoms into fragments. The implementation in the MOLCAS 7.0 quantum chemistry package of the new method, which we call the embedding fragment ab inito model potential method (embedding FAIMP), is reported here, together with results of CASSCF/CASPT2 calculations. The developed methodology is applied for two test problems: (i) the investigation of the lowest ligand field states (2)A(1) and B-2(1) of the Cr(V) defect in the YVO4 crystal and (ii) the investigation of the lowest ligand field and ligand-metal charge transfer (LMCT) states at the Mn(II) substitutional impurity doped into CaCO3. Comparison with similar calculations involving AIMPs for all environmental atoms, including those from covalently bounded units, shows that the FAIMP treatment of the YVO4 units surrounding the CrO43- cluster increases the excitation energy B-2(1) -> (2)A(1) by ca. 1000 cm(-1) at the CASSCF level of calculation. In the case of the Mn(CO3)(6)(10-) cluster, the FAIMP treatment of the CO32- units of the environment give smaller corrections, of ca. 100 cm(-1), for the ligand-field excitation energies, which is explained by the larger ligands of this cluster. However, the correction for the energy of the lowest LMCT transition is found to be ca. 600 cm(-1) for the CASSCF and ca. 1300 cm(-1) for the CASPT2 calculation. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Chemical Theory and Computation
volume
4
issue
4
pages
586 - 594
publisher
The American Chemical Society
external identifiers
  • wos:000254710700005
  • scopus:50849095871
ISSN
1549-9618
DOI
10.1021/ct7003148
language
English
LU publication?
yes
id
ff55eb5c-a4aa-457d-8fd9-8d3c5fbb9454 (old id 1207444)
date added to LUP
2008-08-27 13:45:07
date last changed
2017-04-30 06:49:27
@article{ff55eb5c-a4aa-457d-8fd9-8d3c5fbb9454,
  abstract     = {In this article, we present a fragment model potential approach for the description of the crystalline environment as an extension of the use of embedding ab initio model potentials (AIMPs). The biggest limitation of the embedding AIMP method is the spherical nature of its model potentials. This poses problems as soon as the method is applied to crystals containing strongly covalently bonded structures with highly nonspherical electron densities. The newly proposed method addresses this problem by keeping the full electron density as its model potential, thus allowing one to group sets of covalently bonded atoms into fragments. The implementation in the MOLCAS 7.0 quantum chemistry package of the new method, which we call the embedding fragment ab inito model potential method (embedding FAIMP), is reported here, together with results of CASSCF/CASPT2 calculations. The developed methodology is applied for two test problems: (i) the investigation of the lowest ligand field states (2)A(1) and B-2(1) of the Cr(V) defect in the YVO4 crystal and (ii) the investigation of the lowest ligand field and ligand-metal charge transfer (LMCT) states at the Mn(II) substitutional impurity doped into CaCO3. Comparison with similar calculations involving AIMPs for all environmental atoms, including those from covalently bounded units, shows that the FAIMP treatment of the YVO4 units surrounding the CrO43- cluster increases the excitation energy B-2(1) -> (2)A(1) by ca. 1000 cm(-1) at the CASSCF level of calculation. In the case of the Mn(CO3)(6)(10-) cluster, the FAIMP treatment of the CO32- units of the environment give smaller corrections, of ca. 100 cm(-1), for the ligand-field excitation energies, which is explained by the larger ligands of this cluster. However, the correction for the energy of the lowest LMCT transition is found to be ca. 600 cm(-1) for the CASSCF and ca. 1300 cm(-1) for the CASPT2 calculation.},
  author       = {Swerts, Ben and Chibotaru, Liviu F. and Lindh, Roland and Seijo, Luis and Barandiaran, Zoila and Clima, Sergiu and Pierloot, Kristin and Hendrickx, Marc F. A.},
  issn         = {1549-9618},
  language     = {eng},
  number       = {4},
  pages        = {586--594},
  publisher    = {The American Chemical Society},
  series       = {Journal of Chemical Theory and Computation},
  title        = {Embedding fragment ab initio model potentials in CASSCF/CASPT2 calculations of doped solids: Implementation and applications},
  url          = {http://dx.doi.org/10.1021/ct7003148},
  volume       = {4},
  year         = {2008},
}