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 alpha-, beta(1)-, beta(2)-, gamma-, and delta-carbons from edge to innermost carbon. In PIMD simulation, meanwhile, stable adsorption site is not appeared on delta-carbon, but on only alpha-, beta(1)-, beta(2)-, and gamma-carbons. This result is due to the fact that the adsorbed hydrogen atom can easily go over the barrier for hydrogen transferring from delta- to beta(1)-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. (C) 2010 Elsevier B.V. All rights reserved.