Quantum chemical study of lanthanide and actinide impurities in ionic crystals.
DIPC Seminars
- Speaker
-
Dr. Fernando Ruipérez, Department of Physics, Stockholm University, AlbaNova University Centre, Stockholm, Sweden.
- When
-
2010/04/12
14:00 - Place
- onostia International Physics Center (DIPC).Paseo Manuel de Lardizabal, 4 (nearby the Facultad de Quimica), Donostia
- Add to calendar
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The interest on the f(n) , f(n-1)d(1) and f(n-1)s(1) local electronic states
of lanthanide and actinide impurities in ionic crystals has been growing in
the last few years. The electronic transitions which occur upon visible and UV
excitation are involved in a variety of phenomena of technological interest
which are not always fully understood. Thus, theory and experiments become
particularly complementary in this context.
It is nowadays possible to calculate the local geometry around an f-element
impurity in an ionic host at ambient and high pressures from first principles,
using wavefunction based methods of relativistic quantum chemistry in
combination with quantum mechanical embedding. The accuracy of the theoretical
results can only be assured if the methods fulfill the following requirements:
relativistic effects including spin-orbit coupling must be considered
simultaneously with valence electron correlation. Finally, the effects of the
embedding host crystal must be considered as well. These requirements are met
by the ab initio model potential method (AIMP),[1] which is formulated as an
effective core potential method that can include spin-orbit relativistic
effects and also as an embedding technique useful to describe the quantum
mechanical effects of a set of host lattice ions which are represented as
Hartree-Fock wavefunctions occupying crystal sites. The method has been widely
tested and applied to transition metal and heavy metal impurities in ionic
hosts.[2]
In this seminar, results in the study of the structure and spectroscopy of U3+
and Ce3+ doped in Cs2NaYCl6 crystals will be presented, as well as the effect
of high pressures in these properties.[3]
[1] L. Seijo and Z. Barandiarán, in Computational Chemistry: Reviews of
Current Trends, edited by J. Leszczynski (World Scienti.c, Singapore 1999),
vol. 4, pag. 55.
[2] L. Seijo and Z. Barandiarán, J. Chem. Phys. 89, 5739 (1988); L. Seijo and
Z. Barandiarán, J. Chem. Phys. 115, 5554 (2001); J. L. Pascual, Z.
Barandiarán, and L. Seijo J. Chem. Phys. 124, 124315 (2006).
[3] F. Ruipérez, Z. Barandiarán, and L. Seijo, J. Chem. Phys. 122, 234507
(2005); F. Ruipérez, Z. Barandiarán, and L. Seijo, J. Chem. Phys. 127
144712 (2007).