Nuclear quantum effect on hydrogen adsorption site of zeolite-templated carbon model using path integral molecular dynamics

To settle the hydrogen adsorption sites on buckybowl C36H12, which is picked up from zeolite-templated carbon (ZTC), we have performed path integral molecular dynamics (PIMD) simulation including thermal and nuclear quantum fluctuations under semi-empirical PM3 method. In the static PM3 calculation and classical simulation the five stable adsorption sites of hydrogen atom are optimized inside a buckybowl C36H12, which are labeled as α-, β1-, β2-, γ-, and δ-carbons from edge to innermost carbon. In PIMD simulation, meanwhile, stable adsorption site is not appeared on δ-carbon, but on only α-, β1-, β2-, and γ-carbons. This result is due to the fact that the adsorbed hydrogen atom can easily go over the barrier for hydrogen transferring from δ- to β1-carbons by thermal and nuclear quantum fluctuations. The thermal and nuclear quantum effects are key role to settle the hydrogen adsorption sites on carbon materials.

Research highlights▶ The stable hydrogen adsorption sites on C36H12 were evaluated at 300 K using path integral molecular dynamics. ▶ In the static MO calculation and conventional MD simulation, five stable adsorption sites of hydrogen atom were found. ▶ In path integral simulation, only four stable adsorption sites were obtained. ▶ The thermal and nuclear quantum effects are key role to settle the hydrogen adsorption sites on carbon materials.