Ezequiel Leiva - Academia.edu (original) (raw)

Papers by Ezequiel Leiva

Resumen. En este trabajo se presentan el desarrollo de un prototipo autónomo de generación eléctr... more Resumen. En este trabajo se presentan el desarrollo de un prototipo autónomo de generación eléctrica, capaz de producir hidrógeno a partir de energía eólica. Este sistema consiste en un aerogenerador de eje horizontal de 2 kW de potencia, que entrega corriente alterna trifásica al equipo productor de hidrógeno (electrolizador). El electrolizador es de tipo alcalino y está adaptado a las características del aerogenerador a quien está conectado en forma directa. En esta primera etapa de evaluación del prototipo los gases producidos por el electrolizador son venteados a la atmósfera.

The predictive power of molecular dynamic simulations is mainly restricted by the time scale and ... more The predictive power of molecular dynamic simulations is mainly restricted by the time scale and model accuracy. Many systems of current relevance are of such complexity that requires addressing both issues simultaneously. This is the case of silicon electrodes in Li-ion batteries, where different Li$_x$Si alloys are formed during charge/discharge cycles. While first-principles treatments for this system are seriously limited by the computational cost of exploring its large conformational space, classical force-fields are not transferable enough to represent it accurately. Density Functional Tight-Binding (DFTB) is an intermediate complexity approach capable of capturing the electronic nature of different environments with a relatively low computational cost. In this work, we present a new set of DFTB parameters suited to model amorphous Li$_x$Si alloys. The latter is the usual finding upon cycling the Si electrodes in the presence of Li-ions. The model parameters are constructed wi...

Progress in Energy, 2021

Since 1994, Kinetic Monte Carlo (kMC) has been applied to the study of Li-ion batteries and has d... more Since 1994, Kinetic Monte Carlo (kMC) has been applied to the study of Li-ion batteries and has demonstrated to be a remarkable simulation tool to properly describe the physicochemical processes involved, on the atomistic scale and over long time scales. With the growth of computing power and the widespread use of lithium-based storage systems, more contributions from theoretical studies have been requested. This has led to a remarkable growth of theoretical publications on Li-ion batteries; kMC has been one of the preferred techniques to study these systems. Despite the advantages it presents, kMC has not yet been fully exploited in the field of lithium-ion batteries and its impact in this field is increasing exponentially. In this review, we summarize the most important applications of kMC to the study of lithium-ion batteries and then comment on the state-of-the-art and prospects for the future of this technique, in the context of multi-scale modeling. We also briefly discuss the prospects for applying kMC to post lithium-ion chemistries such as lithium-sulfur and lithium-air.

Electrochimica Acta, 2019

Understanding the role of the phase transitions during lithiation and delithiation of graphite re... more Understanding the role of the phase transitions during lithiation and delithiation of graphite remains a problem of fundamental importance, but also practical relevance owing to its widespread use as the anode material in most commercial lithium-ion cells. Previously performed density functional theory (DFT) calculations show a rapid change in the lithium-carbon interaction at low occupation, due to partial charge transfer from Li to C. We integrate this effect in our previously developed two level mean field model, which describes the Stage I-Stage II transition in graphite. The modified model additionally describes the most predominant transition that occurs at low Li content in graphite, which results in a previously unexplained feature in voltage and dQ/dV profiles, and thermodynamic measurements of partial molar enthalpy. In contrast with the Stage I-Stage II transition, this extra feature is not associated with observable features in the partial molar entropy and our model demonstrates why. There is a sharp change in the open circuit voltage at very low Li occupation, followed by a transition to a voltage plateau (peak in dQ/dV). The behaviour arises due to the contrasting effects of the partial molar entropy and enthalpy terms on the partial molar Gibbs energy and hence cell voltage. Hence the voltage profile and phase transitions can be approximated for all lithium occupations, potentially allowing a predictive capability in cell level models.

ChemPhysChem, 2021

Understanding and optimization of single particle rate behaviour is normally challenging in compo... more Understanding and optimization of single particle rate behaviour is normally challenging in composite commercial lithium-ion electrode materials. In this regard, recent experimental research has addressed the electrochemical Li-ion intercalation in individual nanosized particles. Here, we present a thorough theoretical analysis of the Li + intercalation voltammetric behaviour in single nano/micro-scale LiMn 2 O 4 (LMO) particles, incorporating realistic interactions between inserted ions. A transparent 2-dimensional zone diagram representation of kinetic-diffusional behaviour is provided that allows rapid diagnosis of the reversibility and diffusion length of the system dependent on particle geometry. We provide an Excel file where the boundary lines of the zone diagram can be rapidly recalculated by setting input values of the rate constant, k 0 and diffusion coefficient, D . The model framework elucidates the heterogeneous behaviour of nanosized particles with similar sizes but different shapes. Hence, we present here an outlook for realistic multiscale modelling of real materials.

Journal of Physics: Condensed Matter, 2021

Lithium–sulfur batteries are considered one of the possible next-generation energy-storage soluti... more Lithium–sulfur batteries are considered one of the possible next-generation energy-storage solutions, but to be commercially available many drawbacks have yet to be solved. One solution with great potentiality is the use of lithium sulfide as cathode material since it can be coupled to Li-free anodes, such as graphite, Si or Sn. Nevertheless, Li2S, like sulfur, is electronically and ionically insulating, with a high activation potential for its initial oxidation step. To overcome this issue, different strategies have been explored, one of them being the use of catalytic surfaces. In the present article, we study using first principles calculations the effect of the dielectric constant of the solvent on the activation energy of the cleavage reaction of Li2S on different catalytic surfaces. To the best of our knowledge, this is the first time that such a study is undertaken. We find that the effect of the solvent should be twofold: on one side, it should decrease the interaction between the Li2S molecule and the surface. On the other side, since the species arising in the dissociation reaction are charged, the solvent should decrease the activation barrier for the dissociation of the Li2S molecule, when compared with the reaction in vacuum. These theoretical findings are discussed in connection with experimental results from the literature, where the behaviour of the Li–S cathode is studied in different solvents.

ACS Applied Energy Materials, 2020

Lithium (Li) metal has been considered as an important anode candidate to reach more powerful ene... more Lithium (Li) metal has been considered as an important anode candidate to reach more powerful energy storage devices with higher gravimetric and volumetric capacities. Nevertheless, the growth of high surface area lithium (HSAL) and dendrites during the stripping / deposition of Li causes safety concern and low cycle life of Li metal batteries. Here we report the obtained results for protection of metallic lithium surface by using a gel polymer ionic liquid cross-linked by activation with UV radiation (UV-PIL). The UV-PIL protects Li against a constant degradation caused by the formation of unstable lithium metal-electrolyte interphase and cell dry out due to continuous electrolyte consumption. We observed retarded growth of dendrites when lithium metal is protected with UV-PIL and due to the lower ionic conductivity of UV-PIL some differences of mass transport are present compared to carbonate based liquid electrolyte. Nevertheless, the UV-PIL@Li negative electrode was successfully applied in a Li-ion battery with lithium iron phosphate (LFP) positive electrode, showing similar behavior compared to the bare Li surface.

XXX Congreso de ASADES (San Luis, 13 al 16 de noviembre de 2007), 2007

RESUMEN. Según estimaciones recientes, los recursos necesarios para atender la demanda de energía... more RESUMEN. Según estimaciones recientes, los recursos necesarios para atender la demanda de energía a nivel nacional son muy limitados, encontrándose el margen de las reservas de combustible fósil líquido y gaseoso en el orden de los 10 años. Además de la criticidad en la disponibilidad de recursos para atender una demanda creciente, el estado de desarrollo actual provoca fuertes impactos ambientales a nivel local y global, a partir del uso intensivo de fuentes fósiles. Ante la situación descripta y con el interés de aportar al conocimiento de la realidad política, social y económica de nuestra provincia en particular y nuestro país en general, se informan en este trabajo las primeras estimaciones-en el contexto del proyecto-del recurso eólico en la provincia de Córdoba con miras a evaluar la viabilidad técnica, económica y ambiental de la producción de Hidrógeno. Estos estudios realizados mediante mediciones de campo, caracterizan la zona estudiada como de buen potencial eólico.

Journal of Solid State Electrochemistry

Revista Tecnología y Ciencia, 2019

El propósito del presente estudio es el diseño de sistemas energéticos híbridos eólico-hidrógeno ... more El propósito del presente estudio es el diseño de sistemas energéticos híbridos eólico-hidrógeno para su comparación con un sistema basado en el uso de combustible fósil solamente. Dicho estudio se aplicó a la localidad "Tres lagos", provincia de Santa Cruz, Argentina. La herramienta utilizada para el análisis y diseño del sistema es el programa de uso libre HOMER® el cual optimiza el funcionamiento de un sistema microenergético particular para cada hora del año utilizando datos de equipos seleccionados por el modelador y considerando parámetros de energías renovables como la velocidad y distribución de velocidades de viento.

Physical Chemistry Chemical Physics, 2010

to analyze the extension of thermodynamics of small systems to metastable states, we have adopted... more to analyze the extension of thermodynamics of small systems to metastable states, we have adopted the same basic ideas to study the thermodynamic stability of core-shell nanoparticles. For the first time we are able to address the question of whether or not core-shell nanoparticles have a limit of stability when they are under oversaturation conditions. By the latter, we mean the excess of chemical potential of the adsorbate (shell) atoms with respect to its bulk material, which is the driving force for nanoparticle growth. In this situation the probability density exhibits multiple local maxima associated with different core-shell metastable states. The decrease of the free energy barriers for the growth of the bulk phase of the shell material is analyzed for increasing oversaturation. At large positive oversaturations, the barrier disappears and the core-shell NP become unstable with respect to the bulk deposit of the shell material. A brief discussion on the model is made illustrating its application to a specific system by means of computer simulations using realistic interatomic potentials. One of the most striking results of these specific studies is the occurrence or not of a core-shell under undersaturation conditions depending on nanoparticle size.

Electrochimica Acta, 1999

Simulation studies are undertaken for the system Ag/Au(100) by means of grand canonical Monte Car... more Simulation studies are undertaken for the system Ag/Au(100) by means of grand canonical Monte Carlo applied to a large lattice system. The interactions are calculated using the embedded atom model. The formation of adsorbed Ag phases of low dimensionality on Ag(100) is investigated and the influence of surface defects on the shape of the adsorption isotherms is studied. The results of the simulations are discussed in the light of experimental information available from electrochemical measurements.

Electrochimica Acta, 2010

In the present work we discuss the statistical mechanical framework for predicting the decoration... more In the present work we discuss the statistical mechanical framework for predicting the decoration of metallic nanoparticles using electrochemical methods, in thermodynamic equilibrium. It is found that depending on the interactions between the two metals, controlled decoration may be achieved for core-shell nanoparticles in undersaturation and oversaturation conditions. The concept of underpotential deposition is discussed for the case of nanoparticles, with the finding that this phenomenon may be size dependent.

Electrochimica Acta, 2012

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit:

Electrochemistry Communications, 2012

Electrochimica Acta, 2014

ABSTRACT The effect of milling time on the morphology of graphite is characterized by XRD, SEM, B... more ABSTRACT The effect of milling time on the morphology of graphite is characterized by XRD, SEM, BET, FTIR and XPS and the electrochemical response of the resulting materials upon lithium-ion absorption is analyzed using different techniques. As milling time is increased, the particle size diminishes and the amount of oxygen content increases. Concomitantly, the capacity for lithium adsorption also increases because new adsorption sites become available due to more surface area and oxygen functional groups. These effects are interpreted using first-principles calculations, which show that the presence of oxygenated species promotes lithium adsorption at higher potentials. This capacity increase is probably not relevant for lithium-ion batteries since there is no intercalation process but rather an adsorption one, but may be of interest for supercapacitive applications. Diffusion coefficients of lithium for different graphite particle sizes are evaluated. The effects of diffusion, particle size and oxygen content are discussed.

We perform high quality, first principles calculations of the properties of Pb and Tl isolated mo... more We perform high quality, first principles calculations of the properties of Pb and Tl isolated monolayers. Among these, we consider the equilibrium lattice constant, the two dimensional compressibilities and the electronic density. Comparison is made with previous results obtained using more simplified models. The present results represent an improvement concerning the calculated compressibilities; these remaining still lower than the measured values. We speculate that the latter could be due to some corrugation of the monolayer, not considered in the present modeling.

Resumen. En este trabajo se presentan el desarrollo de un prototipo autónomo de generación eléctr... more Resumen. En este trabajo se presentan el desarrollo de un prototipo autónomo de generación eléctrica, capaz de producir hidrógeno a partir de energía eólica. Este sistema consiste en un aerogenerador de eje horizontal de 2 kW de potencia, que entrega corriente alterna trifásica al equipo productor de hidrógeno (electrolizador). El electrolizador es de tipo alcalino y está adaptado a las características del aerogenerador a quien está conectado en forma directa. En esta primera etapa de evaluación del prototipo los gases producidos por el electrolizador son venteados a la atmósfera.

The predictive power of molecular dynamic simulations is mainly restricted by the time scale and ... more The predictive power of molecular dynamic simulations is mainly restricted by the time scale and model accuracy. Many systems of current relevance are of such complexity that requires addressing both issues simultaneously. This is the case of silicon electrodes in Li-ion batteries, where different Li$_x$Si alloys are formed during charge/discharge cycles. While first-principles treatments for this system are seriously limited by the computational cost of exploring its large conformational space, classical force-fields are not transferable enough to represent it accurately. Density Functional Tight-Binding (DFTB) is an intermediate complexity approach capable of capturing the electronic nature of different environments with a relatively low computational cost. In this work, we present a new set of DFTB parameters suited to model amorphous Li$_x$Si alloys. The latter is the usual finding upon cycling the Si electrodes in the presence of Li-ions. The model parameters are constructed wi...

Progress in Energy, 2021

Since 1994, Kinetic Monte Carlo (kMC) has been applied to the study of Li-ion batteries and has d... more Since 1994, Kinetic Monte Carlo (kMC) has been applied to the study of Li-ion batteries and has demonstrated to be a remarkable simulation tool to properly describe the physicochemical processes involved, on the atomistic scale and over long time scales. With the growth of computing power and the widespread use of lithium-based storage systems, more contributions from theoretical studies have been requested. This has led to a remarkable growth of theoretical publications on Li-ion batteries; kMC has been one of the preferred techniques to study these systems. Despite the advantages it presents, kMC has not yet been fully exploited in the field of lithium-ion batteries and its impact in this field is increasing exponentially. In this review, we summarize the most important applications of kMC to the study of lithium-ion batteries and then comment on the state-of-the-art and prospects for the future of this technique, in the context of multi-scale modeling. We also briefly discuss the prospects for applying kMC to post lithium-ion chemistries such as lithium-sulfur and lithium-air.

Electrochimica Acta, 2019

Understanding the role of the phase transitions during lithiation and delithiation of graphite re... more Understanding the role of the phase transitions during lithiation and delithiation of graphite remains a problem of fundamental importance, but also practical relevance owing to its widespread use as the anode material in most commercial lithium-ion cells. Previously performed density functional theory (DFT) calculations show a rapid change in the lithium-carbon interaction at low occupation, due to partial charge transfer from Li to C. We integrate this effect in our previously developed two level mean field model, which describes the Stage I-Stage II transition in graphite. The modified model additionally describes the most predominant transition that occurs at low Li content in graphite, which results in a previously unexplained feature in voltage and dQ/dV profiles, and thermodynamic measurements of partial molar enthalpy. In contrast with the Stage I-Stage II transition, this extra feature is not associated with observable features in the partial molar entropy and our model demonstrates why. There is a sharp change in the open circuit voltage at very low Li occupation, followed by a transition to a voltage plateau (peak in dQ/dV). The behaviour arises due to the contrasting effects of the partial molar entropy and enthalpy terms on the partial molar Gibbs energy and hence cell voltage. Hence the voltage profile and phase transitions can be approximated for all lithium occupations, potentially allowing a predictive capability in cell level models.

ChemPhysChem, 2021

Understanding and optimization of single particle rate behaviour is normally challenging in compo... more Understanding and optimization of single particle rate behaviour is normally challenging in composite commercial lithium-ion electrode materials. In this regard, recent experimental research has addressed the electrochemical Li-ion intercalation in individual nanosized particles. Here, we present a thorough theoretical analysis of the Li + intercalation voltammetric behaviour in single nano/micro-scale LiMn 2 O 4 (LMO) particles, incorporating realistic interactions between inserted ions. A transparent 2-dimensional zone diagram representation of kinetic-diffusional behaviour is provided that allows rapid diagnosis of the reversibility and diffusion length of the system dependent on particle geometry. We provide an Excel file where the boundary lines of the zone diagram can be rapidly recalculated by setting input values of the rate constant, k 0 and diffusion coefficient, D . The model framework elucidates the heterogeneous behaviour of nanosized particles with similar sizes but different shapes. Hence, we present here an outlook for realistic multiscale modelling of real materials.

Journal of Physics: Condensed Matter, 2021

Lithium–sulfur batteries are considered one of the possible next-generation energy-storage soluti... more Lithium–sulfur batteries are considered one of the possible next-generation energy-storage solutions, but to be commercially available many drawbacks have yet to be solved. One solution with great potentiality is the use of lithium sulfide as cathode material since it can be coupled to Li-free anodes, such as graphite, Si or Sn. Nevertheless, Li2S, like sulfur, is electronically and ionically insulating, with a high activation potential for its initial oxidation step. To overcome this issue, different strategies have been explored, one of them being the use of catalytic surfaces. In the present article, we study using first principles calculations the effect of the dielectric constant of the solvent on the activation energy of the cleavage reaction of Li2S on different catalytic surfaces. To the best of our knowledge, this is the first time that such a study is undertaken. We find that the effect of the solvent should be twofold: on one side, it should decrease the interaction between the Li2S molecule and the surface. On the other side, since the species arising in the dissociation reaction are charged, the solvent should decrease the activation barrier for the dissociation of the Li2S molecule, when compared with the reaction in vacuum. These theoretical findings are discussed in connection with experimental results from the literature, where the behaviour of the Li–S cathode is studied in different solvents.

ACS Applied Energy Materials, 2020

Lithium (Li) metal has been considered as an important anode candidate to reach more powerful ene... more Lithium (Li) metal has been considered as an important anode candidate to reach more powerful energy storage devices with higher gravimetric and volumetric capacities. Nevertheless, the growth of high surface area lithium (HSAL) and dendrites during the stripping / deposition of Li causes safety concern and low cycle life of Li metal batteries. Here we report the obtained results for protection of metallic lithium surface by using a gel polymer ionic liquid cross-linked by activation with UV radiation (UV-PIL). The UV-PIL protects Li against a constant degradation caused by the formation of unstable lithium metal-electrolyte interphase and cell dry out due to continuous electrolyte consumption. We observed retarded growth of dendrites when lithium metal is protected with UV-PIL and due to the lower ionic conductivity of UV-PIL some differences of mass transport are present compared to carbonate based liquid electrolyte. Nevertheless, the UV-PIL@Li negative electrode was successfully applied in a Li-ion battery with lithium iron phosphate (LFP) positive electrode, showing similar behavior compared to the bare Li surface.

XXX Congreso de ASADES (San Luis, 13 al 16 de noviembre de 2007), 2007

RESUMEN. Según estimaciones recientes, los recursos necesarios para atender la demanda de energía... more RESUMEN. Según estimaciones recientes, los recursos necesarios para atender la demanda de energía a nivel nacional son muy limitados, encontrándose el margen de las reservas de combustible fósil líquido y gaseoso en el orden de los 10 años. Además de la criticidad en la disponibilidad de recursos para atender una demanda creciente, el estado de desarrollo actual provoca fuertes impactos ambientales a nivel local y global, a partir del uso intensivo de fuentes fósiles. Ante la situación descripta y con el interés de aportar al conocimiento de la realidad política, social y económica de nuestra provincia en particular y nuestro país en general, se informan en este trabajo las primeras estimaciones-en el contexto del proyecto-del recurso eólico en la provincia de Córdoba con miras a evaluar la viabilidad técnica, económica y ambiental de la producción de Hidrógeno. Estos estudios realizados mediante mediciones de campo, caracterizan la zona estudiada como de buen potencial eólico.

Journal of Solid State Electrochemistry

Revista Tecnología y Ciencia, 2019

El propósito del presente estudio es el diseño de sistemas energéticos híbridos eólico-hidrógeno ... more El propósito del presente estudio es el diseño de sistemas energéticos híbridos eólico-hidrógeno para su comparación con un sistema basado en el uso de combustible fósil solamente. Dicho estudio se aplicó a la localidad "Tres lagos", provincia de Santa Cruz, Argentina. La herramienta utilizada para el análisis y diseño del sistema es el programa de uso libre HOMER® el cual optimiza el funcionamiento de un sistema microenergético particular para cada hora del año utilizando datos de equipos seleccionados por el modelador y considerando parámetros de energías renovables como la velocidad y distribución de velocidades de viento.

Physical Chemistry Chemical Physics, 2010

to analyze the extension of thermodynamics of small systems to metastable states, we have adopted... more to analyze the extension of thermodynamics of small systems to metastable states, we have adopted the same basic ideas to study the thermodynamic stability of core-shell nanoparticles. For the first time we are able to address the question of whether or not core-shell nanoparticles have a limit of stability when they are under oversaturation conditions. By the latter, we mean the excess of chemical potential of the adsorbate (shell) atoms with respect to its bulk material, which is the driving force for nanoparticle growth. In this situation the probability density exhibits multiple local maxima associated with different core-shell metastable states. The decrease of the free energy barriers for the growth of the bulk phase of the shell material is analyzed for increasing oversaturation. At large positive oversaturations, the barrier disappears and the core-shell NP become unstable with respect to the bulk deposit of the shell material. A brief discussion on the model is made illustrating its application to a specific system by means of computer simulations using realistic interatomic potentials. One of the most striking results of these specific studies is the occurrence or not of a core-shell under undersaturation conditions depending on nanoparticle size.

Electrochimica Acta, 1999

Simulation studies are undertaken for the system Ag/Au(100) by means of grand canonical Monte Car... more Simulation studies are undertaken for the system Ag/Au(100) by means of grand canonical Monte Carlo applied to a large lattice system. The interactions are calculated using the embedded atom model. The formation of adsorbed Ag phases of low dimensionality on Ag(100) is investigated and the influence of surface defects on the shape of the adsorption isotherms is studied. The results of the simulations are discussed in the light of experimental information available from electrochemical measurements.

Electrochimica Acta, 2010

In the present work we discuss the statistical mechanical framework for predicting the decoration... more In the present work we discuss the statistical mechanical framework for predicting the decoration of metallic nanoparticles using electrochemical methods, in thermodynamic equilibrium. It is found that depending on the interactions between the two metals, controlled decoration may be achieved for core-shell nanoparticles in undersaturation and oversaturation conditions. The concept of underpotential deposition is discussed for the case of nanoparticles, with the finding that this phenomenon may be size dependent.

Electrochimica Acta, 2012

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit:

Electrochemistry Communications, 2012

Electrochimica Acta, 2014

ABSTRACT The effect of milling time on the morphology of graphite is characterized by XRD, SEM, B... more ABSTRACT The effect of milling time on the morphology of graphite is characterized by XRD, SEM, BET, FTIR and XPS and the electrochemical response of the resulting materials upon lithium-ion absorption is analyzed using different techniques. As milling time is increased, the particle size diminishes and the amount of oxygen content increases. Concomitantly, the capacity for lithium adsorption also increases because new adsorption sites become available due to more surface area and oxygen functional groups. These effects are interpreted using first-principles calculations, which show that the presence of oxygenated species promotes lithium adsorption at higher potentials. This capacity increase is probably not relevant for lithium-ion batteries since there is no intercalation process but rather an adsorption one, but may be of interest for supercapacitive applications. Diffusion coefficients of lithium for different graphite particle sizes are evaluated. The effects of diffusion, particle size and oxygen content are discussed.

We perform high quality, first principles calculations of the properties of Pb and Tl isolated mo... more We perform high quality, first principles calculations of the properties of Pb and Tl isolated monolayers. Among these, we consider the equilibrium lattice constant, the two dimensional compressibilities and the electronic density. Comparison is made with previous results obtained using more simplified models. The present results represent an improvement concerning the calculated compressibilities; these remaining still lower than the measured values. We speculate that the latter could be due to some corrugation of the monolayer, not considered in the present modeling.