Numerical treatment discussion and ab initio computational reinvestigation of physisorption of molecular hydrogen on graphene.

Abstract

This computational study re-examined the physisorption energy of molecular hydrogen on graphene using ab initio molecular orbital theory under a rigid monomer supermolecular framework. The graphene surface was approximated by a coronene-like cluster (C24H12), and basis set superposition error was addressed via the counterpoise correction. Systematic evaluation of basis set and electron correlation combinations—including aug-cc-pVQZ and coupled cluster with single, double, and perturbative triple excitations—identified asymmetric and local modeling strategies as computationally efficient. An asymmetric scheme employing aug-cc-pVTZ for the adsorbate and nearest substrate atoms, with cc-pVTZ for remaining atoms at the MP2 level, was selected as the reference treatment. The resulting physisorption energy was approximately 0.06 eV, roughly 25% below previously published values, while prior reference data were found to carry errors on the order of 60%. Despite the lower energy estimate, carbon-based physisorptive hydrogen storage remains energetically feasible according to these calculations.

Mechanism

Dispersion-dominated physisorption of H2 on graphene was recalculated at the MP2/aug-cc-pVTZ level, yielding approximately 0.06 eV. Prior overestimates were attributed to inadequate numerical treatment and basis set superposition errors.