Modeling the physisorption of graphene on metals

Abstract

Many processes of technological and fundamental importance occur on surfaces. Adsorption is one of these phenomena that has received the most attention. However, it presents a great challenge to conventional density functional theory. Starting with the Lifshitz-Zaremba-Kohn second-order perturbation theory, here we develop a long-range van der Waals (vdW) correction for physisorption of graphene on metals. The model importantly includes quadrupole-surface interaction and screening effects. The results show that, when the vdW correction is combined with the Perdew-Burke-Enzerhof functional, it yields adsorption energies in good agreement with the random-phase approximation, significantly improving upon other vdW methods. We also find that, compared with the leading-order interaction, the higher-order quadrupole-surface correction accounts for about 25% of the total vdW correction, suggesting the importance of the higher-order term.

Molecule-surface interaction from van der Waals-corrected semilocal density functionals: The example of thiophene on transition-metal surfaces

“…Experiments59 for adsorption of thiophene over copper suggest a range of tilt angle of 20• ±3 • at the coverage of 0.05 ML, and25•±4 • at the coverage of 0.1 ML. Our PBE+vdW-dZK results giving the tilt angle of 17 • at the most stable site at the coverage of 0.0625 ML, agree very well with the experiments.The minimum Cu-S distance of 2.57 Å that we show in Table2from the PBE+vdW-dZK method based on LZK theory40 is in close agreement to the experiments 59. Though both SCAN and revSCAN predict slightly longer Cu-S distance, SCAN+rVV10 and revS-CAN+rVV10 results are closer to the experiments.…”

“…Here in this work we use an approximation that is robust enough and mimics the RPA binding energies almost perfectly for the interaction of graphene and metal surfaces. This approximation 40 , which we will call PBE+vdW-dZK from this point onwards, models the long-range van der Waals correction for physisorption of graphene on metals with the damped Zaremba-Kohn (ZK) 41,42 second-order perturbation theory. In this model, quadrupole-surface interactions and screening effects are included.…”

van der Waals Correction to the Physisorption of Graphene on Metal Surfaces

“…However, because graphene displays sp 2 hybridization, 62 the s electrons may also be involved in the polarization processes, together with p electrons. So, the valence 4 is also reasonable 58, 63,64 and is used in this work, although valence 2 40,65 provides results as accurate as those of valence 4. The unit cell volume is V cell = abc, with b = a sin(π/3) and c being the vdW thickness of graphene, which is set at 3.4 bohr.…”

“…There are two carbon atoms in the unit cell of graphene. In our previous work, 40 the number of valence electron for each carbon atom was 2, as in ref 61. However, because graphene displays sp 2 hybridization, 62 the s electrons may also be involved in the polarization processes, together with p electrons.…”

“…In previous work, 40 we have developed a model of longrange vdW correction for physisorption of graphene on metals with the Lifshitz−Zaremba−Kohn second-order perturbation theory. In this model.…”