Suchergebnisse

The non-monotonic behavior of the electron repulsion energy and the inter-electronic distance, as a function of the internuclear separation, in the 3πu excited state of the hydrogen molecule has been assessed by explicit calculation and analysis of the electron-pair density distribution functions from high level ab initio full configuration interaction wave functions, for both the 3πu and the 1πu states. Additionally, Hund's rule as applied to these two states has been accounted for in terms of simple electronic shielding effects induced by wave function antisymmetrization ; This research has been funded by Euskal Herriko Unibertsitatea (the Univer- sity of the Basque Country), Eusko Jaurlaritza (the Basque Government) and the Spanish Office of Science and Technology (MINECO CTQ2014-52525-P)

We analyze the Coulomb hole of Ne from highly-accurate CISD wave functions obtained from optimized even-tempered basis sets. Using a two-fold extrapolation procedure we obtain highly accurate results that recover 97% of the correlation energy. We confirm the existence of a shoulder in the short-range region of the Coulomb hole of the Ne atom, which is due to an internal reorganization of the K-shell caused by electron correlation of the core electrons. The feature is very sensitive to the quality of the basis set in the core region and it is not exclusive to Ne, being also present in most of second-row atoms, thus confirming that it is due to K-shell correlation effects ; This research has been funded by the Spanish MINECO/FEDER Projects CTQ2014-52525-P (E.M.), CTQ2017-85341-P (M.S.), CTQ2015-67608-P (X.L.), CTQ2015-67660-P (J.M.U.) and EUIN2017- 88605 (E.M.), the Basque Country Consolidated Group Project No. IT588-13, and the Generalitat de Catalunya (Project 2017SGR39, Xarxa de Referència en Química Teòrica i Computacional, and the ICREA Academia 2014 prize (M.S.)). The FEDER grant UNGI10-4E801 (European fund for Regional Development) has also supported this research. M.R.M. acknowledges the Spanish Ministry of Education, Culture and Sports for the doctoral grants FPU-2013/ 00176. E.R.C. and E.M. acknowledge funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement (No. 660943).