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Papers by MOHAMMED GUERBOUB

Research paper thumbnail of Structural properties of amorphous Na$_3$OCl electrolyte by first-principles and machine learning molecular dynamics

arXiv (Cornell University), Apr 17, 2024

Solid-state electrolytes mark a significant leap forward in the field of electrochemical energy s... more Solid-state electrolytes mark a significant leap forward in the field of electrochemical energy storage, offering improved safety and efficiency compared to conventional liquid electrolytes. Among these, antiperovskite electrolytes, particularly those based on Li and Na, have emerged as promising candidates due to their superior ionic conductivity and straightforward synthesis processes. This study focuses on the amorphous phase of antiperovskite Na3OCl, assessing its structural properties through a combination of first-principles molecular dynamics (FPMD) and machine learning interatomic potential (MLIP) simulations. Our comprehensive analysis spans models ranging from 135 to 3645 atoms, allowing for a detailed examination of X-ray and neutron structure factors, total and partial pair correlation functions, coordination numbers, and structural unit distributions. We demonstrate the minimal, albeit partially present, size effects on these structural features and validate the accuracy of the MLIP model in reproducing the intricate details of the amorphous Na3OCl structure described at the FPMD level.

Research paper thumbnail of Thermal conductivity of crystalline Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>5</sub>: lattice contribution and size effects in the cubic phase quantified by approach-to-equilibrium molecular dynamics

Journal of physics. D, Applied physics, Mar 7, 2024

Research paper thumbnail of On the actual difference between the Nosé and the Nosé‐Hoover thermostats : a critical review of canonical temperature control by molecular dynamics

physica status solidi (b)

This paper has to be intended both as a review and as an historical tribute to the ideas develope... more This paper has to be intended both as a review and as an historical tribute to the ideas developed almost forty years ago by S. Nosé establishing the theoretical foundations of the implementation and use of thermostats in molecular dynamics. The original motivation of this work is enriched by an observation related to the connection between the Nosé seminal expression of temperature control and the extension proposed in 1985 by W. G. Hoover, known as the Nosé‐Hoover thermostat. By carefully rederiving the equations of motion in both formalisms, it appears that all features of Nosé‐Hoover framework (replacement of the Nosé variables by a single friction coefficient in the equations of motion) are already built in the Nosé approach. Therefore, one is able to work directly within the Nosé formalism with the addition of a single variable only, by greatly extending its general impact and simplicity and somewhat making redundant the Nosé‐Hoover extension. Having been implicitly (and somew...

Research paper thumbnail of Unveiling the structure and ion dynamics of amorphous Na3−xOHxCl antiperovskite electrolytes by first-principles molecular dynamics

Journal of Materials Chemistry A

Amorphous antiperovskites show potential as solid-state electrolytes due to their versatile prope... more Amorphous antiperovskites show potential as solid-state electrolytes due to their versatile properties. Using first-principles molecular dynamics, we reveal the Na3−xOHxCl system's structural complexities, Na ion dynamics, H atom role, and ionic conductivity mechanisms.

Research paper thumbnail of Graphene Oxide Concentration Effect on the Optoelectronic Properties of ZnO/GO Nanocomposites

Nanomaterials

In this work, the effects of graphene oxide (GO) concentrations (1.5 wt.%, 2.5 wt.%, and 5 wt.%) ... more In this work, the effects of graphene oxide (GO) concentrations (1.5 wt.%, 2.5 wt.%, and 5 wt.%) on the structural, morphological, optical, and luminescence properties of zinc oxide nanorods (ZnO NRs)/GO nanocomposites, synthesized by a facile hydrothermal process, were investigated. X-ray diffraction (XRD) patterns of NRs revealed the hexagonal wurtzite structure for all composites with an average coherence length of about 40–60 nm. A scanning electron microscopy (SEM) study confirmed the presence of transparent and wrinkled, dense GO nanosheets among flower-like ZnO nanorods, depending on the GO amounts used in preparation. Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible (UV–Vis) absorption spectroscopy, and photoluminescence (PL) measurements revealed the impact of GO concentration on the optical and luminescence properties of ZnO NRs/GO nanocomposites. The energy band gap of the ZnO nanorods was independent of GO concentration. Photolumine...

Research paper thumbnail of Structural properties of amorphous Na$_3$OCl electrolyte by first-principles and machine learning molecular dynamics

arXiv (Cornell University), Apr 17, 2024

Solid-state electrolytes mark a significant leap forward in the field of electrochemical energy s... more Solid-state electrolytes mark a significant leap forward in the field of electrochemical energy storage, offering improved safety and efficiency compared to conventional liquid electrolytes. Among these, antiperovskite electrolytes, particularly those based on Li and Na, have emerged as promising candidates due to their superior ionic conductivity and straightforward synthesis processes. This study focuses on the amorphous phase of antiperovskite Na3OCl, assessing its structural properties through a combination of first-principles molecular dynamics (FPMD) and machine learning interatomic potential (MLIP) simulations. Our comprehensive analysis spans models ranging from 135 to 3645 atoms, allowing for a detailed examination of X-ray and neutron structure factors, total and partial pair correlation functions, coordination numbers, and structural unit distributions. We demonstrate the minimal, albeit partially present, size effects on these structural features and validate the accuracy of the MLIP model in reproducing the intricate details of the amorphous Na3OCl structure described at the FPMD level.

Research paper thumbnail of Thermal conductivity of crystalline Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>5</sub>: lattice contribution and size effects in the cubic phase quantified by approach-to-equilibrium molecular dynamics

Journal of physics. D, Applied physics, Mar 7, 2024

Research paper thumbnail of On the actual difference between the Nosé and the Nosé‐Hoover thermostats : a critical review of canonical temperature control by molecular dynamics

physica status solidi (b)

This paper has to be intended both as a review and as an historical tribute to the ideas develope... more This paper has to be intended both as a review and as an historical tribute to the ideas developed almost forty years ago by S. Nosé establishing the theoretical foundations of the implementation and use of thermostats in molecular dynamics. The original motivation of this work is enriched by an observation related to the connection between the Nosé seminal expression of temperature control and the extension proposed in 1985 by W. G. Hoover, known as the Nosé‐Hoover thermostat. By carefully rederiving the equations of motion in both formalisms, it appears that all features of Nosé‐Hoover framework (replacement of the Nosé variables by a single friction coefficient in the equations of motion) are already built in the Nosé approach. Therefore, one is able to work directly within the Nosé formalism with the addition of a single variable only, by greatly extending its general impact and simplicity and somewhat making redundant the Nosé‐Hoover extension. Having been implicitly (and somew...

Research paper thumbnail of Unveiling the structure and ion dynamics of amorphous Na3−xOHxCl antiperovskite electrolytes by first-principles molecular dynamics

Journal of Materials Chemistry A

Amorphous antiperovskites show potential as solid-state electrolytes due to their versatile prope... more Amorphous antiperovskites show potential as solid-state electrolytes due to their versatile properties. Using first-principles molecular dynamics, we reveal the Na3−xOHxCl system's structural complexities, Na ion dynamics, H atom role, and ionic conductivity mechanisms.

Research paper thumbnail of Graphene Oxide Concentration Effect on the Optoelectronic Properties of ZnO/GO Nanocomposites

Nanomaterials

In this work, the effects of graphene oxide (GO) concentrations (1.5 wt.%, 2.5 wt.%, and 5 wt.%) ... more In this work, the effects of graphene oxide (GO) concentrations (1.5 wt.%, 2.5 wt.%, and 5 wt.%) on the structural, morphological, optical, and luminescence properties of zinc oxide nanorods (ZnO NRs)/GO nanocomposites, synthesized by a facile hydrothermal process, were investigated. X-ray diffraction (XRD) patterns of NRs revealed the hexagonal wurtzite structure for all composites with an average coherence length of about 40–60 nm. A scanning electron microscopy (SEM) study confirmed the presence of transparent and wrinkled, dense GO nanosheets among flower-like ZnO nanorods, depending on the GO amounts used in preparation. Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible (UV–Vis) absorption spectroscopy, and photoluminescence (PL) measurements revealed the impact of GO concentration on the optical and luminescence properties of ZnO NRs/GO nanocomposites. The energy band gap of the ZnO nanorods was independent of GO concentration. Photolumine...