showing 7 related works from this author
Grand Canonical Monte Carlo Simulations to Determine the Optimal Interlayer Distance of a Graphene Slit-Shaped Pore for Adsorption of Methane, Hydrog…
2021
The adsorption—for separation, storage and transportation—of methane, hydrogen and their mixture is important for a sustainable energy consumption in present-day society. Graphene derivatives have proven to be very promising for such an application, yet for a good design a better understanding of the optimal pore size is needed. In this work, grand canonical Monte Carlo simulations, employing Improved Lennard–Jones potentials, are performed to determine the ideal interlayer distance for a slit-shaped graphene pore in a large pressure range. A detailed study of the adsorption behavior of methane, hydrogen and their equimolar mixture in different sizes of graphene pores is obtained through ca…
Potential models for the simulation of methane adsorption on graphene: development and CCSD(T) benchmarks
2018
Different force fields for the graphene–CH4 system are proposed including pseudo-atom and full atomistic models. Furthermore, different charge schemes are tested to evaluate the electrostatic interaction for the CH4 dimer. The interaction parameters are optimized by fitting to interaction energies at the DFT level, which were themselves benchmarked against CCSD(T) calculations. The potentials obtained with both the pseudo-atom and full atomistic approaches describe accurately enough the average interaction in the methane dimer as well as in the graphene–methane system. Moreover, the atom–atom potentials also correctly provide the energies associated with different orientations of the molecu…
Modeling the Interaction of Carbon Monoxide with Flexible Graphene: From Coupled Cluster Calculations to Molecular-Dynamics Simulations
2018
The interaction of CO with graphene was studied at different theoretical levels. Quantum-mechanical calculations on finite graphene models with the use of coronene for coupled cluster calculations and circumcoronene for B97D calculations showed that there was no preferential site for adsorption and that the most important factor was the orientation of CO relative to graphene. The parallel orientation was preferred, with binding energies around 9 kJ mol-1 at the CCSD(T) and B97D levels, which was in good agreement with experimental findings. From a large number of CO-circumcoronene and CO-CO interactions, computed at different distances and randomly generated orientations, parameters were fi…
Nitrogen Gas on Graphene: Pairwise Interaction Potentials
2018
We investigate different types of potential parameters for the graphene-nitrogen interaction. Interaction energies calculated at DFT level are fitted with the semi-emperical Improved Lennard-Jones potential. Both a pseudo-atom potential and a full atomistic potential are considered. Furthermore, we consider the influence of the electrostatic part on the parameters using different charge schemes found in the literature as well as optimizing the charges ourselves. We have obtained parameters for both the nitrogen dimer and the graphene-nitrogen system. For the former, the four-charges Cracknell scheme reproduces with high precision the CCSD(T) interaction energy as well as the experimental di…
Flexibility in the Graphene Sheet: The Influence on Gas Adsorption from Molecular Dynamics Studies
2019
Despite being considered completely rigid in most studies, graphene is really flexible leading to out-of-plane movements. In this work, the influence of such flexibility on the adsorption of methane and nitrogen on graphene is studied using molecular dynamics. Indeed, we have used intramolecular force fields for graphene with in-plane and out-of-plane components that allow for describing the movements and deformations of the graphene sheets and providing a more realistic description of the adsorbent. In addition, intermolecular force fields validated at the CCSD(T) level are used. We show that considering the movement of graphene in the adsorption study significantly improves the performanc…
Molecular dynamics of CH4/N2 mixtures on a flexible graphene layer: adsorption and selectivity case study
2019
We theoretically investigate graphene layers, proposing them as membranes of subnanometer size suitable for CH4/N2 separation and gas uptake. The observed potential energy surfaces, representing the intermolecular interactions within the CH4/N2 gaseous mixtures and between these and the graphene layers, have been formulated by adopting the so-called Improved Lennard-Jones (ILJ) potential, which is far more accurate than the traditional Lennard-Jones potential. Previously derived ILJ force fields are used to perform extensive molecular dynamics simulations on graphene's ability to separate and adsorb the CH4/N2 mixture. Furthermore, the intramolecular interactions within graphene were explic…
Modeling the Interaction of Light Gases with Graphene: From Coupled Cluster Calculations to Molecular Dynamics Simulations
2019
El estudio de la adsorción de gases sobre grafeno ha suscitado gran interés debido a sus aplicaciones en el almacenamiento de energía, sensores gaseosos y separación de gases. Los gases ligeros interactúan con el grafeno mediante interacciones no covalentes, las cuales, debido a su débil naturaleza y corto alcance, son aún difíciles de describir con precisión por los métodos teóricos. La presente Tesis Doctoral está dedicada a obtener potenciales simples, pero muy fiables, para modelizar la adsorción de gases sobre grafeno, para posteriormente evaluarlos en simulaciones de sistemas relevantes para aplicaciones industriales. En primer lugar, se estudió con metodologías de alta nivel (DFT y C…