Person:
Fernández Abascal, José Luis

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First Name
José Luis
Last Name
Fernández Abascal
URI
https://hdl.handle.net/20.500.14352/76142
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Area
Química Física
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2015 - 201912020 - 20232
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Start date: 2015 × Has files: true ×

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Now showing 1 - 3 of 3
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    Teoría de perturbaciones de fluidos moleculares
    (2015) Fernández Abascal, José Luis
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    “In Silico” Seawater
    (Journal of Chemical Theory and Computation, 2021) Zeron, Iván M.; González, Miguel A.; Errani, Edoardo; Vega de las Heras, Carlos; Fernández Abascal, José Luis
    Many important processes affecting the earth’s climate are determined by the physical properties of seawater. In addition, desalination of seawater is a significant source of drinking water for the human population living in coastal areas. Since the physical properties of seawater governing these processes depend on the molecular interactions among its components, a deeper knowledge of seawater at the molecular level would contribute to a better understanding of these phenomena. However, in strong contrast with the situation in other areas such as biomolecules or materials science, molecular simulation studies reporting the physical properties of seawater are currently lacking. This is probably due to the usual perception of the seawater composition being too complex to approach. This point of view ignores the fact that physical properties of seawater are dependent on a single parameter representing the composition, namely the salinity. This is because the relative proportions of any two major constituents of seasalt are always the same. Another obstacle to performing molecular simulations of seawater could have been the unavailability of a satisfactory force field representing the interactions between water molecules and dissolved substances. However, this drawback has recently been overcome with the proposal of the Madrid-2019 force field. In this work we show for the first time that molecular simulation of seawater is feasible. We have performed molecular dynamics simulations of a system, the composition of which is close to the average composition of standard seawater and with the molecular interactions given by the Madrid-2019 force field. In this way we are able to provide quantitative or semiquantitative predictions for a number of relevant physical properties of seawater for temperatures and salinities from the oceanographic range to those relevant to desalination processes. The computed magnitudes include static (density), dynamical (viscosity and diffusion coefficients), structural (ionic hydration, ion−ion distribution functions), and interfacial (surface tension) properties.
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    On the computation of electrical conductivities of aqueous electrolyte solutions: Two surfaces one property
    (Journal of Chemical Theory and Computation, 2023) Blázquez Fernández, Samuel; Fernández Abascal, José Luis; Lagerweij, Jelle; Habibi, Parsa; Dey, Poloumy; Vlugt, Thijs; Moultos, Othonas; Vega De Las Heras, Carlos
    In this work, we have computed electrical conductivities at ambient conditions of aqueous NaCl and KCl solutions by using the Einstein-Helfand equation. Common force fields (charge q =±1 e) do not reproduce the experimental values of electrical conductivities, viscosities and diffusion coefficients. Recently, we proposed the idea of using different charges to describe the Potential Energy Surface (PES) and the Dipole Moment Surface (DMS). In this work, we implement this concept. The equilibrium trajectories required to evaluate electrical conductivities (within linear response theory) were obtained by using scaled charges (with the value q =±0.75 e) to describe the PES. The potential parameters were those of the Madrid-Transport force field, which describe accurately viscosities and diffusion coefficients of these ionic solutions. However, integer charges were used to compute the conductivities (thus describing the DMS). The basic idea is that although the scaled charge describes the ion-water interaction better, the integer charge reflects the value of the charge that is transported due to the electric field. The agreement obtained with experiments is excellent, as for the first time electrical conductivities (and the other transport properties) of NaCl and KCl electrolyte solutions are described with high accuracy for the whole concentration range up to their solubility limit. Finally, we propose an easy way to obtain a rough estimate of the actual electrical conductivity of the potential model under consideration using the approximate Nernst-Einstein equation, which neglects correlations between different ions.