Evy Salcedo - Academia.edu (original) (raw)

Papers by Evy Salcedo

Nanotechnology, Oct 7, 2009

Journal of Applied Physics, Jul 1, 2008

Journal of Applied Physics, Jul 1, 2008

Journal of Chemical Physics, Dec 24, 2020

Journal of Chemical Physics, Jan 14, 2020

arXiv (Cornell University), May 31, 2010

Using molecular dynamic simulations we study a system of particles interacting through a continuo... more Using molecular dynamic simulations we study a system of particles interacting through a continuous core-softened potentials consisting of a hard core, a shoulder at closest distances and an attractive well at further distance. We obtain the pressure-temperature phase diagram of of this system for various depths of the tunable attractive well. Since this is a two length scales potential, density, diffusion and structural anomalies are expected. We show that the effect of increasing the attractive interaction between the molecules is to shrink the region in pressure in which the density and the diffusion anomalies are present. If the attractive forces are too strong, particle will be predominantly in one of the two length scales and no density of diffusion anomaly is observed. The structural anomalous region is present for all the cases.

Asymmetric hysteresis loop in magnetostatic-biased multilayer nanowires

The Journal of Chemical Physics, 2020

In this article, we investigate, through molecular dynamics simulations, the diffusion behavior o... more In this article, we investigate, through molecular dynamics simulations, the diffusion behavior of the TIP4P/2005 water confined in pristine and deformed carbon nanotubes (armchair and zigzag). To analyze different diffusive mechanisms, the water temperature was varied as 210 ≤ T ≤ 380 K. The results of our simulations reveal that water presents a non-Arrhenius to Arrhenius diffusion crossover. The confinement shifts the diffusion transition to higher temperatures when compared with the bulk system. In addition, for narrower nanotubes, water diffuses in a single line, which leads to its mobility independent of the activation energy.

The Journal of Chemical Physics, 2020

We use molecular dynamics simulations to study the diffusion of water inside deformed carbon nano... more We use molecular dynamics simulations to study the diffusion of water inside deformed carbon nanotubes with different degrees of deformation at 300 K. We found that the number of hydrogen bonds that water forms depends on nanotube topology, leading to enhancement or suppression of water diffusion. The simulation results reveal that more realistic nanotubes should be considered to understand the confined water diffusion behavior, at least for the narrowest nanotubes, when the interaction between water molecules and carbon atoms is relevant.

Physical review. E, 2018

The slip of a fluid layer in contact with a solid confining surface is investigated for different... more The slip of a fluid layer in contact with a solid confining surface is investigated for different temperatures and densities using molecular dynamic simulations. We show that for an anomalous waterlike fluid the slip goes as follows: for low levels of shear, defect slip appears and is related to the particle exchange between the fluid layers; at high levels of shear, global slip occurs and is related to the homogeneous distribution of the fluid in the confining surfaces. The oscillations in the transition velocity from defect to global slip are shown to be associated with changes in the layering distribution in the anomalous fluid.

The Journal of Chemical Physics, 2017

In this work, we used a generalized Frenkel-Kontorova model to study the mobility of water molecu... more In this work, we used a generalized Frenkel-Kontorova model to study the mobility of water molecules inside carbon nanotubes with small radius at low temperatures. Our simulations show that the mobility of confined water decreases monotonically increasing the amplitude of the substrate potential at fixed commensurations. On the other hand, the mobility of the water molecules shows a non-monotonic behavior when varying the commensuration. This result indicates that the mobility of the confined fluid presents different behavior regimes depending on the amplitude of the water–nanotube interaction. In order to qualitatively understand these results, we study analytically the driven Frenkel-Kontorova model at finite temperatures. This analysis allows us to obtain the curves of the mobility versus commensurations, at fixed substrate potentials. Such curves show the existence of three regimes of mobility behavior as a function of the commensuration ratio. Additionally, our study indicates ...

The pioneer work of Krim and Widom (J. Krim, and A. Widom, Phys. Rev. B 38), 12184 (1988). that u... more The pioneer work of Krim and Widom (J. Krim, and A. Widom, Phys. Rev. B 38), 12184 (1988). that unveiled the viscous nature of friction at the atomic scale, generated extensive experimental and theoretical activity. However, fundamental questions remain open like the relation between sliding friction and the topology of the substrate, as well as the dependence on the temperature

Nanotechnology, 2009

The hysteresis of multilayer nanowires composed by a soft magnetic cylindrical wire, a non-magnet... more The hysteresis of multilayer nanowires composed by a soft magnetic cylindrical wire, a non-magnetic spacer layer and an external hard magnetic shell is investigated. The external magnetic shell originates a non-homogeneous magnetic field on the inner wire, which is responsible for a displacement and a change of the width of the hysteresis curve of the wire. Moreover, different reversal modes occur at each branch of the hysteresis loop, which can be understood by analyzing the interaction magnetostatic field along the wire. Our results open the possibility of controlling two parameters of the hysteresis loop, the coercivity and the bias, providing an interesting system to be investigated.

Journal of Applied Physics, 2008

The field driven nucleation and propagation of transverse domain walls in a uniform Ni nanowire i... more The field driven nucleation and propagation of transverse domain walls in a uniform Ni nanowire is examined by means of Monte Carlo simulations combined with a scaling technique. Simulations show a nonlinear behavior followed by the simultaneous nucleation of several domain walls. Also we study the angular dependence of the propagation of the transverse domain wall with external field. Results are analyzed in terms of the classical relaxation model for interface dynamics.

The European Physical Journal B, 2008

Applied Physics Letters, 2007

The magnetic switching of ferromagnetic nanotubes is investigated as a function of their geometry... more The magnetic switching of ferromagnetic nanotubes is investigated as a function of their geometry. Two independent methods are used: Numerical simulations and analytical calculations. It is found that for long tubes the reversal of magnetization is achieved by two mechanisms: The propagation of a transverse domain wall or propagation of a vortex domain wall depending on the internal and external radii of the tube.

Applied Physics Letters, 2007

The magnetic switching of ferromagnetic nanotubes is investigated as a function of their geometry... more The magnetic switching of ferromagnetic nanotubes is investigated as a function of their geometry. Two independent methods are used: Numerical simulations and analytical calculations. It is found that for long tubes the reversal of magnetization is achieved by two mechanisms: The propagation of a transverse domain wall or propagation of a vortex domain wall depending on the internal and external radii of the tube.

Journal of Chemical Sciences, 2017

Starting from an anomalous monomeric system, where particles interact via a two-scale coresoftene... more Starting from an anomalous monomeric system, where particles interact via a two-scale coresoftened potential, we investigate how the system properties evolve inasmuch as particles are put together to form polymers whose chain size varies from 4 up to 32 monomers. We observed that the density and diffusion anomaly regions in the pressure versus temperature phase diagram of the monomeric system is smaller in the monomeric system when compared with the polymers. We also found that the polymers do not fold into themselves to form solid spheres instead they tend to maximize the chain-fluid contact. Also, Rouse and Reptation models can be employed to describe the polymers diffusive behaviour. But, in contrast to results of simulations where mere interacts via Lennard-Jones potentials, our results shown a much shorter entanglement length of at most 8 monomers.

The Journal of chemical physics, Jan 7, 2009

Using molecular dynamic simulations we study a family of continuous core-softened potentials cons... more Using molecular dynamic simulations we study a family of continuous core-softened potentials consisting of a hard core, a shoulder at closest distances, and an attractive well at further distance. The repulsive shoulder and the well distances represent two length scales. We show that if the first scale, the shoulder, is repulsive or has a small well, the potential has a region in the pressure-temperature phase diagram with density, diffusion, and structural anomalies. However, if the closest scale becomes a deep well, the regions in the pressure-temperature phase diagram where the three anomalies are present shrink and disappear. This result helps in defining two length scales potentials that exhibit anomalies.

Nanotechnology, Oct 7, 2009

Journal of Applied Physics, Jul 1, 2008

Journal of Applied Physics, Jul 1, 2008

Journal of Chemical Physics, Dec 24, 2020

Journal of Chemical Physics, Jan 14, 2020

arXiv (Cornell University), May 31, 2010

Using molecular dynamic simulations we study a system of particles interacting through a continuo... more Using molecular dynamic simulations we study a system of particles interacting through a continuous core-softened potentials consisting of a hard core, a shoulder at closest distances and an attractive well at further distance. We obtain the pressure-temperature phase diagram of of this system for various depths of the tunable attractive well. Since this is a two length scales potential, density, diffusion and structural anomalies are expected. We show that the effect of increasing the attractive interaction between the molecules is to shrink the region in pressure in which the density and the diffusion anomalies are present. If the attractive forces are too strong, particle will be predominantly in one of the two length scales and no density of diffusion anomaly is observed. The structural anomalous region is present for all the cases.

Asymmetric hysteresis loop in magnetostatic-biased multilayer nanowires

The Journal of Chemical Physics, 2020

In this article, we investigate, through molecular dynamics simulations, the diffusion behavior o... more In this article, we investigate, through molecular dynamics simulations, the diffusion behavior of the TIP4P/2005 water confined in pristine and deformed carbon nanotubes (armchair and zigzag). To analyze different diffusive mechanisms, the water temperature was varied as 210 ≤ T ≤ 380 K. The results of our simulations reveal that water presents a non-Arrhenius to Arrhenius diffusion crossover. The confinement shifts the diffusion transition to higher temperatures when compared with the bulk system. In addition, for narrower nanotubes, water diffuses in a single line, which leads to its mobility independent of the activation energy.

The Journal of Chemical Physics, 2020

We use molecular dynamics simulations to study the diffusion of water inside deformed carbon nano... more We use molecular dynamics simulations to study the diffusion of water inside deformed carbon nanotubes with different degrees of deformation at 300 K. We found that the number of hydrogen bonds that water forms depends on nanotube topology, leading to enhancement or suppression of water diffusion. The simulation results reveal that more realistic nanotubes should be considered to understand the confined water diffusion behavior, at least for the narrowest nanotubes, when the interaction between water molecules and carbon atoms is relevant.

Physical review. E, 2018

The slip of a fluid layer in contact with a solid confining surface is investigated for different... more The slip of a fluid layer in contact with a solid confining surface is investigated for different temperatures and densities using molecular dynamic simulations. We show that for an anomalous waterlike fluid the slip goes as follows: for low levels of shear, defect slip appears and is related to the particle exchange between the fluid layers; at high levels of shear, global slip occurs and is related to the homogeneous distribution of the fluid in the confining surfaces. The oscillations in the transition velocity from defect to global slip are shown to be associated with changes in the layering distribution in the anomalous fluid.

The Journal of Chemical Physics, 2017

In this work, we used a generalized Frenkel-Kontorova model to study the mobility of water molecu... more In this work, we used a generalized Frenkel-Kontorova model to study the mobility of water molecules inside carbon nanotubes with small radius at low temperatures. Our simulations show that the mobility of confined water decreases monotonically increasing the amplitude of the substrate potential at fixed commensurations. On the other hand, the mobility of the water molecules shows a non-monotonic behavior when varying the commensuration. This result indicates that the mobility of the confined fluid presents different behavior regimes depending on the amplitude of the water–nanotube interaction. In order to qualitatively understand these results, we study analytically the driven Frenkel-Kontorova model at finite temperatures. This analysis allows us to obtain the curves of the mobility versus commensurations, at fixed substrate potentials. Such curves show the existence of three regimes of mobility behavior as a function of the commensuration ratio. Additionally, our study indicates ...

The pioneer work of Krim and Widom (J. Krim, and A. Widom, Phys. Rev. B 38), 12184 (1988). that u... more The pioneer work of Krim and Widom (J. Krim, and A. Widom, Phys. Rev. B 38), 12184 (1988). that unveiled the viscous nature of friction at the atomic scale, generated extensive experimental and theoretical activity. However, fundamental questions remain open like the relation between sliding friction and the topology of the substrate, as well as the dependence on the temperature

Nanotechnology, 2009

The hysteresis of multilayer nanowires composed by a soft magnetic cylindrical wire, a non-magnet... more The hysteresis of multilayer nanowires composed by a soft magnetic cylindrical wire, a non-magnetic spacer layer and an external hard magnetic shell is investigated. The external magnetic shell originates a non-homogeneous magnetic field on the inner wire, which is responsible for a displacement and a change of the width of the hysteresis curve of the wire. Moreover, different reversal modes occur at each branch of the hysteresis loop, which can be understood by analyzing the interaction magnetostatic field along the wire. Our results open the possibility of controlling two parameters of the hysteresis loop, the coercivity and the bias, providing an interesting system to be investigated.

Journal of Applied Physics, 2008

The field driven nucleation and propagation of transverse domain walls in a uniform Ni nanowire i... more The field driven nucleation and propagation of transverse domain walls in a uniform Ni nanowire is examined by means of Monte Carlo simulations combined with a scaling technique. Simulations show a nonlinear behavior followed by the simultaneous nucleation of several domain walls. Also we study the angular dependence of the propagation of the transverse domain wall with external field. Results are analyzed in terms of the classical relaxation model for interface dynamics.

The European Physical Journal B, 2008

Applied Physics Letters, 2007

The magnetic switching of ferromagnetic nanotubes is investigated as a function of their geometry... more The magnetic switching of ferromagnetic nanotubes is investigated as a function of their geometry. Two independent methods are used: Numerical simulations and analytical calculations. It is found that for long tubes the reversal of magnetization is achieved by two mechanisms: The propagation of a transverse domain wall or propagation of a vortex domain wall depending on the internal and external radii of the tube.

Applied Physics Letters, 2007

The magnetic switching of ferromagnetic nanotubes is investigated as a function of their geometry... more The magnetic switching of ferromagnetic nanotubes is investigated as a function of their geometry. Two independent methods are used: Numerical simulations and analytical calculations. It is found that for long tubes the reversal of magnetization is achieved by two mechanisms: The propagation of a transverse domain wall or propagation of a vortex domain wall depending on the internal and external radii of the tube.

Journal of Chemical Sciences, 2017

Starting from an anomalous monomeric system, where particles interact via a two-scale coresoftene... more Starting from an anomalous monomeric system, where particles interact via a two-scale coresoftened potential, we investigate how the system properties evolve inasmuch as particles are put together to form polymers whose chain size varies from 4 up to 32 monomers. We observed that the density and diffusion anomaly regions in the pressure versus temperature phase diagram of the monomeric system is smaller in the monomeric system when compared with the polymers. We also found that the polymers do not fold into themselves to form solid spheres instead they tend to maximize the chain-fluid contact. Also, Rouse and Reptation models can be employed to describe the polymers diffusive behaviour. But, in contrast to results of simulations where mere interacts via Lennard-Jones potentials, our results shown a much shorter entanglement length of at most 8 monomers.

The Journal of chemical physics, Jan 7, 2009

Using molecular dynamic simulations we study a family of continuous core-softened potentials cons... more Using molecular dynamic simulations we study a family of continuous core-softened potentials consisting of a hard core, a shoulder at closest distances, and an attractive well at further distance. The repulsive shoulder and the well distances represent two length scales. We show that if the first scale, the shoulder, is repulsive or has a small well, the potential has a region in the pressure-temperature phase diagram with density, diffusion, and structural anomalies. However, if the closest scale becomes a deep well, the regions in the pressure-temperature phase diagram where the three anomalies are present shrink and disappear. This result helps in defining two length scales potentials that exhibit anomalies.