caa a22 4500 605512485 CHVBK 20210128100655.0 cr unu---uuuuu 210128e20150401xx s 000 0 eng 10.1007/s00894-015-2611-7 doi (NATIONALLICENCE)springer-10.1007/s00894-015-2611-7 Relative stabilities of HCl•H2SO4•HNO3 aggregates in polar stratospheric clouds [Elektronische Daten] [Marian Verdes, M. Paniagua] Strong acids such as HCl (C), HNO3 (N) and H2SO4 (S) acquire relevance in Polar Stratospheric Clouds (PSCs) and aerosols in which nucleation processes occur. Ab initio quantum chemical studies of aggregates were performed for these strong acids. Structures were calculated using DFT methods with the B3LYP hybrid functional and aug-cc-pVTZ basis set. As an initial constraint, an H2SO4 moiety was placed in all candidate structures. A total of 11 optimized structures was found: a global minimum (CSN-a) plus ten local minima on the Potential Energy Surface (PES). The global minimum aggregate gave four hydrogen bonds, yielding a hexagonal ring in its structure. HNO3 acts as proton donor in all clusters; nevertheless, using trans-H2SO4 as the proton donor yielded the most stable structures, whereas HCl acts mainly as a proton donor/acceptor. Real harmonic frequencies, IR spectra, and inter-monomeric parameters were obtained. CSN-a symmetric stretching modes were shifted to 2805.56cm−1 and 3520.00cm−1 for H-Cl modes, while O-H modes shifted to 3256.87cm−1 and 3362.47cm−1. On the other hand, relative stabilities improved for 5 of the 11 aggregates when the temperature decreased from 298 Kto 210K, 195K and 188K. The aggregate CSN-f remained unstable only at 210K. Moreover, the relative Gibbs free energy, ΔG(0-298K) was −9.26 kcalmol−1 with respect to CSN-a; relative reaction Gibbs free energy [Δ(ΔG)] values ranged from 0.0 at 298K, to −6.9kcalmol−1 at 188K. It seems that CSN aggregates remain slightly more stable than CNS aggregates with a HNO3 moiety when the temperature decreases from 298 to 188K. Five structures remained relatively stable under both study conditions. Springer-Verlag Berlin Heidelberg, 2015 DFT nationallicence PSC nationallicence Ab initio nationallicence Sulfuric acid nationallicence Nitric acid nationallicence Hydrogen chloride nationallicence Relative stability nationallicence Gibbs free energy nationallicence Atmospheric temperatures nationallicence Atmospheric aggregates nationallicence Atmospheric clusters nationallicence Atmospheric chemistry nationallicence Thermochemistry nationallicence IR frequencies nationallicence Verdes Marian Departamento de Química Física Aplicada, Facultad de Ciencias, C-14, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain aut Paniagua M. Departamento de Química Física Aplicada, Facultad de Ciencias, C-14, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain aut Journal of Molecular Modeling Springer Berlin Heidelberg 21/4(2015-04-01), 1-22 1610-2940 21:4<1 2015 21 894 https://doi.org/10.1007/s00894-015-2611-7 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00894-015-2611-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Verdes Marian Departamento de Química Física Aplicada, Facultad de Ciencias, C-14, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain aut NATIONALLICENCE 700 1- Paniagua M. Departamento de Química Física Aplicada, Facultad de Ciencias, C-14, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain aut NATIONALLICENCE 773 0- Journal of Molecular Modeling Springer Berlin Heidelberg 21/4(2015-04-01), 1-22 1610-2940 21:4<1 2015 21 894