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Abstract The finite field method using ab initio hybrid functional approach was applied to estimate nonlinear properties of the cluster based on paratellurite crystal structure. The good agreement was found with previously reported data.The method demonstrate high efficiency in prediction of nonlinear properties for a wide ensemble of sufficiently large polyatomic clusters.

International audience

International audience; Query expansion (QE) aims at improving information retrieval effectiveness by enhancing the query formulation. Because users' queries are generally short and because of the language ambiguity, some information needs are difficult to satisfy. Query reformulation and QE methods have been developed to face this issue. Pseudo relevance feedback (PRF) considers the top retrieved documents as relevant and uses their content in order to expand the initial query. Rather than considering feedback documents as a bag of words, it is possible to exploit term proximity information. Although there are some researches in this direction, the majority of them is empirical. The lack of theoretical works in this area motivated us to introduce a novel method integrated into the language model formalism that takes advantage of the remoteness of candidate terms for QE from query terms within feedback documents. In contrast to previous works, our approach captures the proximity directly and in terms of sentences rather than tokens. We show that the method significantly improves the retrieval performance on TREC collections especially for difficult queries.

Starting from an effective Skyrme interaction we present a finite rank separable approach for the QRPA calculations taking into account the effects of the phonon-phonon coupling. As an example the properties of the low-lying quadrupole states in 94Mo are considered. It is shown that the third 2+ state is the mixed-symmetry state.