Crystal field splittings in lanthanide complexes: Inclusion of correlation effects beyond second order perturbation theory

Abstract : State-averaged complete active space self-consistent field (CASSCF) calculations and a subsequent spin-orbit calculation mixing the CASSCF wave functions (CASSCF/state-interaction with spin-orbit coupling) is the conventional approach used for ab initio calculations of crystal-field splittings and magnetic properties of lanthanide complexes. However, this approach neglects dynamical correlation. Complete active space second-order perturbation theory (CASPT2) can be used to account for dynamical correlation, but suffers from the well-known problems of multireference perturbation theory, e.g. intruder state problems. Variational multireference configuration interaction (MRCI) calculations do not show these problems but are usually not feasible due to the large size of real lanthanide complexes. We present a quasi-local projected internally contracted MRCI approach which makes MRCI calculations of lanthanide complexes feasible and allows assessing the influence of dynamical correlation beyond second-order perturbation theory. We apply the method to two well-studied molecules, namely Er[N(SiMe3)2]3 and {C(NH2)3}5[Er(CO3)4]∙11H2O
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https://hal-upec-upem.archives-ouvertes.fr/hal-01826125
Contributor : Alexander Mitrushchenkov <>
Submitted on : Friday, June 29, 2018 - 9:17:54 AM
Last modification on : Thursday, July 18, 2019 - 4:36:07 PM

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Philipp Paul Hallmen, Guntram Rauhut, Hermann Stoll, Alexander Mitrushchenkov, Joris van Slageren. Crystal field splittings in lanthanide complexes: Inclusion of correlation effects beyond second order perturbation theory. Journal of Chemical Theory and Computation, American Chemical Society, 2018, 18 (4), pp.3998-4009. ⟨10.1021/acs.jctc.8b00184⟩. ⟨hal-01826125⟩

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