scholarly journals Electric Field and Temperature Effects on the Ab Initio Spectroscopy of Liquid Methanol

2021 ◽  
Vol 11 (12) ◽  
pp. 5457
Author(s):  
Giuseppe Cassone ◽  
Sebastiano Trusso ◽  
Jiri Sponer ◽  
Franz Saija
Keyword(s):  
Electric Field ◽  
Ab Initio ◽  
Electric Fields ◽  
Ab Initio Molecular Dynamics ◽  
Bulk Liquid ◽  
Field Exposure ◽  
Polar Liquids ◽  
Vibrational Response ◽  
Different Temperatures ◽  
Dynamics Simulations

Although many H-bonded systems have been extensively investigated by means of infrared (IR) spectroscopy, the vibrational response to externally applied electric fields of polar liquids remains poorly investigated. However, local electric fields along with quantum-mechanical interactions rule the behavior of H-bonded samples at the molecular level. Among the many H-bonded systems, liquid methanol holds a key place in that it exhibits a very simple H-bond network where, on average, each molecule acts as a single H-bond donor and, at the same time, as a single H-bond acceptor. Here we report on the IR spectra emerging from a series of state-of-the-art ab initio molecular dynamics simulations of bulk liquid methanol under the action of static and homogeneous electric fields. In addition, the same analysis is here conducted in the absence of the external field and for different temperatures. Although some electric-field-induced effects resemble the response of other polar liquids (such as the global contraction of the IR spectrum upon field exposure), it turns out that, distinctly from water, the “electrofreezing” phenomenon is unlikely to happen in liquid methanol. Finally, we provide atomistic analyses magnifying the completely different nature of electric-field- and temperature-induced effects on bulk liquid methanol and on its vibrational response.

scholarly journals Possibility of realizing superionic ice VII in external electric fields of planetary bodies

2020 ◽  
Vol 6 (21) ◽  
pp. eaaz2915 ◽  
Author(s):  
Zdenek Futera ◽  
John S. Tse ◽  
Niall J. English
Keyword(s):  
Molecular Dynamics ◽  
Electric Field ◽  
Ab Initio ◽  
Electric Fields ◽  
State Of The Art ◽  
Ab Initio Molecular Dynamics ◽  
Theoretical Studies ◽  
Potential Candidate ◽  
External Electric Fields ◽  
Ice Phase

In a superionic (SI) ice phase, oxygen atoms remain crystallographically ordered while protons become fully diffusive as a result of intramolecular dissociation. Ice VII’s importance as a potential candidate for a SI ice phase has been conjectured from anomalous proton diffusivity data. Theoretical studies indicate possible SI prevalence in large-planet mantles (e.g., Uranus and Neptune) and exoplanets. Here, we realize sustainable SI behavior in ice VII by means of externally applied electric fields, using state-of-the-art nonequilibrium ab initio molecular dynamics to witness at first hand the protons’ fluid dance through a dipole-ordered ice VII lattice. We point out the possibility of SI ice VII on Venus, in its strong permanent electric field.

scholarly journals Ab Initio Molecular Dynamics Study of Methanol-Water Mixtures under External Electric Fields

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3371 ◽  
Author(s):  
Giuseppe Cassone ◽  
Adriano Sofia ◽  
Jiri Sponer ◽  
A. Marco Saitta ◽  
Franz Saija
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Electric Fields ◽  
Structural Changes ◽  
Chemical Reactivity ◽  
Pure Water ◽  
Ab Initio Molecular Dynamics ◽  
Sudden Increase ◽  
Molar Ratios ◽  
Dynamics Simulations

Intense electric fields applied on H-bonded systems are able to induce molecular dissociations, proton transfers, and complex chemical reactions. Nevertheless, the effects induced in heterogeneous molecular systems such as methanol-water mixtures are still elusive. Here we report on a series of state-of-the-art ab initio molecular dynamics simulations of liquid methanol-water mixtures at different molar ratios exposed to static electric fields. If, on the one hand, the presence of water increases the proton conductivity of methanol-water mixtures, on the other, it hinders the typical enhancement of the chemical reactivity induced by electric fields. In particular, a sudden increase of the protonic conductivity is recorded when the amount of water exceeds that of methanol in the mixtures, suggesting that important structural changes of the H-bond network occur. By contrast, the field-induced multifaceted chemistry leading to the synthesis of e.g., hydrogen, dimethyl ether, formaldehyde, and methane observed in neat methanol, in 75:25, and equimolar methanol-water mixtures, completely disappears in samples containing an excess of water and in pure water. The presence of water strongly inhibits the chemical reactivity of methanol.

Ab initio molecular dynamics study of an aqueous NaCl solution under an electric field

2016 ◽  
Vol 18 (33) ◽  
pp. 23164-23173 ◽  
Author(s):  
Giuseppe Cassone ◽  
Fabrizio Creazzo ◽  
Paolo V. Giaquinta ◽  
Franz Saija ◽  
A. Marco Saitta
Keyword(s):  
Molecular Dynamics ◽  
Electric Field ◽  
Proton Transfer ◽  
Ab Initio ◽  
Strong Field ◽  
Ab Initio Molecular Dynamics ◽  
Water Dissociation ◽  
Nacl Solution ◽  
Salty Water ◽  
Dynamics Simulations

Ab initio molecular dynamics simulations of salty water under an electric field reveal two regimes of the relative mobilities of chlorine and sodium ions. When water dissociation and proton transfer are actived at strong field intensities, the presence of the ions hinders the efficiency of the proton transfer mechanism.

scholarly journals Ab initio Molecular Dynamics Simulations of Field-Coupled Nanocomputing Molecules

2021 ◽  
Vol 16 (1) ◽  
pp. 1-8
Author(s):  
Yuri Ardesi ◽  
Alessandro Gaeta ◽  
Giuliana Beretta ◽  
Gianluca Piccinini ◽  
Mariagrazia Graziano
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Charge Distribution ◽  
Electric Fields ◽  
Reducing Power ◽  
Ab Initio Molecular Dynamics ◽  
Molecular Vibrations ◽  
Realistic Situation ◽  
Dynamics Simulations ◽  
The Impact

Molecular Field-Coupled Nanocomputing (FCN) represents one of the most promising solutions to overcome the issues introduced by CMOS scaling. It encodes the information in the molecule charge distribution and propagates it through electrostatic intermolecular interaction. The need for charge transport is overcome, hugely reducing power dissipation.At the current state-of-the-art, the analysis of molecular FCN is mostly based on quantum mechanics techniques, or ab initio evaluated transcharacteristics. In all the cases, studies mainly consider the position of charges/atoms to be fixed. In a realistic situation, the position of atoms, thus the geometry, is subjected to molecular vibrations. In this work, we analyse the impact of molecular vibrations on the charge distribution of the 1,4-diallyl butane. We employ Ab Initio Molecular Dynamics to provide qualitative and quantitative results which describe the effects of temperature and electric fields on molecule charge distribution, taking into account the effects of molecular vibrations. The molecules are studied at near-absolute zero, cryogenic and ambient temperature conditions, showing promising results which proceed towards the assessment of the molecular FCN technology as a possible candidate for future low-power digital electronics. From a modelling perspective, the diallyl butane demonstrates good robustness against molecular vibrations, further confirming the possibility to use static transcharacteristics to analyse molecular circuits.

Tuning the Electric Field Response of MOFs by Rotatable Dipolar Linkers

2019 ◽  
Author(s):  
Johannes P. Dürholt ◽  
Babak Farhadi Jahromi ◽  
Rochus Schmid
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Structural Changes ◽  
Dielectric Behavior ◽  
Two Dimensions ◽  
Dielectric Constants ◽  
Electric Response ◽  
Dipole Strength ◽  
Metal Organic ◽  
Dynamics Simulations

Recently the possibility of using electric fields as a further stimulus to trigger structural changes in metal-organic frameworks (MOFs) has been investigated. In general, rotatable groups or other types of mechanical motion can be driven by electric fields. In this study we demonstrate how the electric response of MOFs can be tuned by adding rotatable dipolar linkers, generating a material that exhibits paralectric behavior in two dimensions and dielectric behavior in one dimension. The suitability of four different methods to compute the relative permittivity κ by means of molecular dynamics simulations was validated. The dependency of the permittivity on temperature T and dipole strength μ was determined. It was found that the herein investigated systems exhibit a high degree of tunability and substantially larger dielectric constants as expected for MOFs in general. The temperature dependency of κ obeys the Curie-Weiss law. In addition, the influence of dipolar linkers on the electric field induced breathing behavior was investigated. With increasing dipole moment, lower field strength are required to trigger the contraction. These investigations set the stage for an application of such systems as dielectric sensors, order-disorder ferroelectrics or any scenario where movable dipolar fragments respond to external electric fields.

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