https://hdl.handle.net/2072/453073 Fri, 03 Apr 2026 21:56:18 GMT 2026-04-03T21:56:18Z https://hdl.handle.net/10256/28571 Origin-Independent Decomposition of the Static Polarizability Montilla Busquets, Marc; Luis Luis, Josep Maria; Salvador Sedano, Pedro Real-space analysis tools afford additive and transferable contributions of atoms to molecular properties. In the case of the molecular (hyper)polarizabilities, the atomic contributions that have been derived so far include a charge-transfer term that is origin-dependent. In this letter, we present the first genuinely origin-independent energy-based (OIEB) methodology for the decomposition of the static (hyper)polarizabilities that benefits from real-space molecular energy decomposition schemes, focusing on the static polarizability and showing that extension to static hyperpolarizabilities is straightforward. The numerical realization of the OIEB method shows the expected origin independence, atomic additivity, and transferability of atomic and functional group polarizability tensors. Furthermore, the OIEB atomic (fragment) polarizability tensors are symmetric by definition; This work was supported by the Spanish government MICINN (PGC2018-098212-B-C22), and Generalitat de Catalunya (2017SGR39). We also thank the Generalitat de Catalunya for the predoctoral grant to M.M. (2019 FI_B01001) Tue, 09 Feb 2021 00:00:00 GMT https://hdl.handle.net/10256/28571 2021-02-09T00:00:00Z https://hdl.handle.net/10256/28569 Can Density Functional Theory Be Trusted for High-Order Electric Properties? The Case of Hydrogen-Bonded Complexes Zaleśny, Robert; Medved, Miroslav; Sitkiewicz, Sebastian P.; Matito i Gras, Eduard; Luis Luis, Josep Maria This work reports on an extensive assessment of the performance of a wide palette of density functional approximations in predicting the (high-order) electric properties of hydrogen-bonded complexes. To this end, we compute the electronic and vibrational contributions to the electric polarizability and the first and second hyperpolarizabilities, using the CCSD(T)/aug-cc-pVTZ level of theory as reference. For all the studied properties, the average absolute errors below 20% can only be obtained using the CAM-B3LYP functional, while LC-BLYP and MN15 are shown to be only slightly less accurate (average absolute errors not exceeding 30%). Among Minnesota density functionals, i.e., M06, M06-2X, and MN15, we only recommend the latter one, which quite accurately predicts the electronic and vibrational (hyper)polarizabilities. We also analyze the optimal tuning of the range-separation parameter μ for the LC-BLYP functional, finding that this approach does not bring any systematic improvement in the predictions of electronic and vibrational (hyper)polarizabilities and the accuracy of computed properties is largely system-dependent. Finally, we report huge errors in predicting the vibrational second hyperpolarizability by ωB97X, M06, and M06-2X functionals. Based on the explicit evaluation of anharmonic terms contributing to the second hyperpolarizability, this failure is traced down to a poor determination of third- and fourth-order energy derivatives with respect to normal modes. These results reveal serious flaws of some density functional approximations and suggest caution in selecting the appropriate functional to calculate not only electronic and vibrational (hyper)polarizabilities but also other molecular properties that contain vibrational anharmonic contributions; R.Z. acknowledges financial support by the Polish National Science Centre (Grant No. 2015/19/B/ST4/01881). M.M. acknowledges the Slovak Research and Development Agency (project no. APVV-15-0105) and CMST COST Action CM1405 MOLIM: MOLecules In Motion. J.M.L. and E.M. are grateful for financial support from the Spanish MINECO CTQ2014-52525-P (E.M. and J.M.L.) and EUIN2017-88605 (E.M.), and to the Catalan DIUE 2014SGR931 (J.M.L.). S.P.S. acknowledges the Basque Government for funding through a predoctoral fellowship (PRE 2018 2 0200) Tue, 11 Jun 2019 00:00:00 GMT https://hdl.handle.net/10256/28569 2019-06-11T00:00:00Z https://hdl.handle.net/10256/28353 Expanding aromaticity tests to include lowest-lying triplet excited states and charged and heterocyclic rings Cabrero-Martí, Maria; Solà i Puig, Miquel Aromaticity is a pivotal concept in chemistry arising from electron delocalization in closed-loop systems that confers extra energetic stabilization. Its direct observation is not possible, making its quantification challenging. To address this issue, several methods have been developed to quantify this non-observable property based on various physicochemical properties characteristic of these compounds. However, given the indirect nature of these measures, they do not always yield consistent or reliable aromaticity trends. Therefore, it is important to design tools that help identify which descriptors perform most effectively and put forward their weaknesses and strenghts. In a previous study (F. Feixas, E. Matito, J. Poater, M. Solà, On the performance of some aromaticity indices: a critical assessment using a test set, J. Comput. Chem., 2008, 29(10), 1543–1554.), we introduced a series of fifteen aromaticity tests that were used to analyze the advantages and drawbacks of a group of ten aromaticity descriptors. In this work, we propose to extent these initial tests of aromaticity with a series of thirteen tests related to excited state aromaticity, redox processes, and heterocyclic rings to evaluate the ability of twelve aromaticity descriptors. A comprehensive evaluation of the strengths and weaknesses of the analysed indicators of aromaticity reveals that electronic and magnetic indices perform most consistently, although the former show limitations when applied to oxidized species Wed, 11 Feb 2026 00:00:00 GMT https://hdl.handle.net/10256/28353 2026-02-11T00:00:00Z https://hdl.handle.net/10256/28345 Hypersaline mining effluents affect the structure and function of stream biofilm Vendrell Puigmitja, Lidia; Proia, Lorenzo; Espinosa Angona, Carmen; Barral Fraga, Laura; Cañedo Argüelles, Miguel; Osorio, Victoria; Casas, Carme; Llenas, Laia; Abril, Meritxell La salinització dels ecosistemes d'aigua dolça és un problema ambiental global que amenaça la biodiversitat, el funcionament dels ecosistemes i el benestar humà. L'objectiu d'aquest estudi va ser investigar l'impacte potencial d'un gradient de salinitat realista sobre l'estructura i el funcionament dels biofilms d'aigua dolça. El gradient de salinitat es va basar en la concentració real d'ions d'un efluent miner d'una mina abandonada a Alemanya. Vam exposar biofilm d'un rierol prístin a 5 salinitats creixents (de 3 a 100 g L −1 ) en condicions controlades en rierols artificials durant 21 dies. Vam avaluar les seves respostes funcionals (eficiència fotosintètica, absorció de nutrients i respiració microbiana) i estructurals (composició de la comunitat, biomassa d'algues i mètriques de diatomees, cianobacteris i algues verdes ) al llarg del temps. Després vam comparar les seves respostes amb un biofilm no exposat utilitzat com a control. La funcionalitat i l'estructura del biofilm exposat a les diferents salinitats van disminuir significativament després d'una exposició a curt i llarg termini, respectivament. La composició de la comunitat va canviar a un nou estat estable on les espècies més tolerants van augmentar la seva abundància. Al mateix temps, vam observar un augment de la tolerància comunitària (mesurada com a Tolerància Comunitària Induïda per la Contaminació) al llarg del gradient de salinitat. Aquest estudi proporciona informació rellevant sobre les concentracions llindar de sal que poden danyar substancialment les cèl·lules d'algues (és a dir, entre 15 i 30 g L −1 ). Els resultats proporcionen nous coneixements sobre la resposta i l'adaptació del biofilm de rierol a la salinitat i les seves possibles implicacions a nivell d'ecosistema; This work was supported by the European Commission LIFE program throughout the LIFE DEMINE project (LIFE16 ENV/ES/000218) Sat, 15 Oct 2022 00:00:00 GMT https://hdl.handle.net/10256/28345 2022-10-15T00:00:00Z