Nitrogen Gas on Graphene: Pairwise Interaction Potentials

Abstract

Abstract.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 diffusion coefficient in both the pseudo-atom and full atomstic potential. In the second case, the atom-atom model provides an average interaction energy of 2.3 kcal/mol, comparable with the experimental graphene-N2 interaction of 2.4 kcal/mol.

Potential models for the simulation of methane adsorption on graphene: development and CCSD(T) benchmarks

“…Previous research has shown that coronene and circumcoronene are suitable models to represent graphene at CCSD(T) and B97D levels of theory, respectively. [31][32][33][34] Circumcoronene can be seen as a benzene ring with two concentric rings of benzenes whereby the outermost ring is terminated by dangling hydrogen atoms to avoid wrong electronic structures.…”

“…From a practical point of view, it seems to be a very robust functional and, among semi-empirical GGA functionals, it is suggested as an efficient and precise method for the study of large systems interacting through dispersion forces. 28 Although the B97D functional has proven its value for non-covalent interactions, [28][29][30][31] this does not guarantee accurate results in a systematic manner for all systems. To overcome this issue, we benchmarked important geometries against CCSD(T) calculations that provide the most trustable physical description of non-covalent interactions in computational chemistry and can therefore be used as reference calculations.…”

Molecular Dynamics of CH4/N2 Mixtures on a Flexible Graphene Layer: Adsorption and Selectivity Case Study

“…In this work, we used intermolecular potentials based on the ILJ potential (Pirani et al, 2004, 2008) to describe the interactions between different gas molecules on one hand and the interactions between the gas molecules and the graphene sheet on the other (Vekeman et al, 2018a,b). Furthermore, we implemented intramolecular interaction potentials in DL_POLY v2.2.…”

“…The parameters that were used for the graphene-gas and the gas-gas interactions have been obtained by fitting the ILJ potential, supplemented with a Coulombic sum, to high-level interaction energies at DFT level of the respective systems. The obtained potentials were then benchmarked against DFT and CCSD(T) results as was explained in previous publications (Vekeman et al, 2018a,b). From the results in these articles, here, for both methane and nitrogen, a united-atom and an atomistic model were selected with corresponding partial charges and used for simulations; the used parameters can be found in Table 1.…”

“…The choice between these types of models is thus often a balancing of accuracy and computational cost and therefore their comparison is critical to make informed decisions (Lucena et al, 2010). In previous works, we have derived intramolecular potentials specifically designed for the adsorption of nitrogen and methane on graphene (Vekeman et al, 2018a,b). We based these potentials on the Improved Lennard-Jones potential (ILJ) (Pirani et al, 2004, 2008) as these have shown to outperform the very popular Lennard-Jones (LJ) potential (Pacifici et al, 2013; Faginas-Lago et al, 2015, 2016).…”