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- Swerts, Ben, et al.
(författare)
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Embedding fragment ab initio model potentials in CASSCF/CASPT2 calculations of doped solids : Implementation and applications
- 2008
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Ingår i: Journal of Chemical Theory and Computation. - : American Chemical Society (ACS). - 1549-9618 .- 1549-9626. ; 4:4, s. 586-594
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Tidskriftsartikel (refereegranskat)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.
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| 2. |
- van Buggenhout, Sandra, et al.
(författare)
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Structural design of natural plant based foods to promote nutritional quality
- 2012
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Ingår i: Trends in Food Science and Technology. - : Elsevier BV. - 0924-2244 .- 1879-3053. ; 24:1, s. 47-59
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- During traditional industrial processing of fruit and vegetable derived foods, consideration of the eventual retention, bio-accessibility or bio-availability of nutrients has hitherto been a secondary priority. Indeed standard processing of soups and sauces involves treating all ingredients in a similar way, usually by prolonged heat treatment and results in both lowered nutritional value and sensory quality of food products. Such products are typically structured using various additives including starches, gums and stabilizers, which consumers regard as unnatural, rather than exploiting the endogenous structuring potential of the fruit and vegetable ingredients as available at the farm gate. Recent studies undertaken within the EU sponsored 'Healthy Structuring' project have shown how to design an industrially manufactured product with good sensory qualities that is natural and nutritious. The strategy has been to use the inherent structural and nutritional properties of the raw material ingredients, on the one hand to ensure the textural quality of the final product without the use of artificial gums or stabilizers and, on the other hand to optimize the nutritional quality of the final product. This review briefly summarizes both the approach taken and the results obtained within the project.
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