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Pi, M., Barranco, M., Navarro, J., & Ancilotto, F. (2012). Nucleation and cavitation in parahydrogen. Chem. Phys., 399, 213–217.
Abstract: We have used a density functional approach to investigate thermal homogeneous nucleation and cavitation in parahydrogen. The effect of electrons as seeds of heterogeneous cavitation in liquid parahydrogen is also discussed within the capillary model.
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Ancilotto, F., Barranco, M., Navarro, J., & Pi, M. (2016). A Density Functional Approach to Para-hydrogen at Zero Temperature. J. Low Temp. Phys., 185(1-2), 26–38.
Abstract: We have developed a density functional (DF) built so as to reproduce either the metastable liquid or the solid equation of state of bulk para-hydrogen, as derived from quantum Monte Carlo zero temperature calculations. As an application, we have used it to study the structure and energetics of small para-hydrogen clusters made of up to molecules. We compare our results for liquid clusters with diffusion Monte Carlo (DMC) calculations and find a fair agreement between them. In particular, the transition found within DMC between hollow-core structures for small N values and center-filled structures at higher N values is reproduced. The present DF approach yields results for (pH) clusters indicating that for small N values a liquid-like character of the clusters prevails, while solid-like clusters are instead energetically favored for .
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Leal, A., Mateo, D., Pi, M., Barranco, M., & Navarro, J. (2013). The structure of mixed He-3-He-4 droplets doped with OCS: A density functional approach. J. Chem. Phys., 139(17), 174308–6pp.
Abstract: We have investigated the structure and energetics of mixed He-3-He-4 droplets doped with a carbonyl sulfide molecule within a density functional approach considering a small but finite temperature of 0.1 K. The molecule is treated as an external field to which the helium droplet is attached. The energetics and appearance of these droplets are discussed for selected numbers of helium atoms, identifying the first magic numbers of the fermionic component.
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Mateo, D., Pi, M., Navarro, J., & Toennies, J. P. (2013). A density functional study of the structure of small OCS@He-3(N) clusters. J. Chem. Phys., 138(4), 044321–8pp.
Abstract: Kohn-Sham density functional calculations are reported for the structures of clusters consisting of a carbonyl sulfide (OCS) molecule with N = 1, 8, 18, and 40 attached He-3 atoms. The N = 1 cluster ground state is highly localized at the molecular waist (donut ring position), but for higher levels of excitation becomes increasingly delocalized. The first magic cluster with 8 atoms has a significant density at both ends of the molecule in addition to the donut ring. With N = 18 He-3 atoms the molecule is enclosed by a magic number closed shell. Another magic stable structure consisting of two nearly isotropically spherical closed shells is found at N = 40. A comparison with calculations for the same sized He-4 clusters show some important similarities, e. g., pile up at the donut ring position but altogether a more diffuse, less anisotropic structure. These results are discussed in the light of the recently analyzed infrared spectra measured in large pure He-3 droplets (N approximate to 1.2 x 10(4)) [B. Sartakov, J. P. Toennies, and A. F. Vilesov, J. Chem. Phys. 136, 134316 (2012)]. The moments of inertia of the 11 atom spherical shell structure, which is consistent with the experimental spectrum, lies between the predicted moments of inertia for N = 8 and N = 18 clusters. Overall the calculations reveal that the structures and energies of small doped He-3 are only slightly more diffuse and less energetic than the same He-4 clusters.
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Navarro, J., Ancilotto, F., Barranco, M., & Pi, M. (2011). Toward a Density Functional Description of Liquid pH(2). J. Phys. Chem. A, 115(25), 6910–6917.
Abstract: A finite-temperature density functional approach to describe the properties of parahydrogen in the liquid vapor coexistence region is presented. The first proposed functional is zero-range, where the density-gradient term is adjusted so as to reproduce the surface tension of the liquid vapor interface at low temperature. The second functional is finite-range and, while it is fitted to reproduce bulk pH(2) properties only, it is shown to yield surface properties in good agreement with experiments. These functionals are used to study the surface thickness of the liquid vapor interface, the wetting transition of parahydrogen on a planar Rb model surface, and homogeneous cavitation in bulk liquid pH(2).
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