Theoretical study of the H/D isotope effect of CH4/CD4 adsorption on a Rh(111) surface using a combined plane wave and localized basis sets method.

Hiroki Sakagami,Masanori Tachikawa,Takayoshi Ishimoto

doi:10.1039/d0ra10796d

Hiroki Sakagami, Masanori Tachikawa + Show 1 more

Open Access

https://doi.org/10.1039/d0ra10796d

Copy DOI

Abstract

We analysed the H/D isotope effect of CH4/CD4 adsorption on a Rh(111) surface using our combined plane wave and localized basis sets method, that we proposed for the consideration of delocalized electrons on a surface and the quantum effect of protons (deuterons) in metal–molecule interactions. We observed that the adsorption distance and energy of CD4 were larger and lower than those of CH4, respectively. This is in reasonable agreement with the corresponding experimental results of cyclohexane adsorption. We clearly found that the trend of the H/D isotope effect in the geometrical and energetic difference was similar to that of the hydrogen-bonded systems.

Highlights

The behaviour of atoms and molecules on various surfaces has attracted attention in various elds, including materials science, material physics, and catalytic chemistry
We analysed the H/D isotope effect of CH4/CD4 adsorption on a Rh(111) surface using our combined plane wave and localized basis sets method, that we proposed for the consideration of delocalized electrons on a surface and the quantum effect of protons in metal–molecule interactions
We studied CH4/CD4 adsorption on Rh(111) surface to analyse and understand the H/D isotope effect on the molecules that are adsorbed on metal surfaces

Summary

Introduction

The behaviour of atoms and molecules on various surfaces has attracted attention in various elds, including materials science, material physics, and catalytic chemistry. For the direct treatment of the difference of the NQEs of protons and deuterons, we developed multicomponent molecular orbital and density functional theory (MC_MO and MC_DFT) approaches, which are based on localized orbitals (LOs).[16,17,18] Using these approaches, it is possible to describe the geometrical and electronic structure changes that are induced by H and D.17,19 These approaches are useful in investigating the H/D isotope effects for adsorbed molecules on metal surfaces, the calculation of large systems, such as those de ned by PBCs, is not realistic due to high computational cost. The atomic coordinates of CH4/CD4 were optimised using the CPLB method including the MC_DFT approach as an LO part under the condition of xed Rh atoms on the surface

Results and discussion

Conflicts of interest

Conclusions