Effect of basis set on the outcome of external energy mediated chemical reactions

Directing the energies of an hot-electron or atom or molecule towards a specific vibrational mode to tune the reaction outcomes is an active area of catalytic research and ab initio molecular dynamics is one of the indispensable tools in understanding the mechanistic details of these reactions. In this work, we show that the predicted thermodynamic and catalytic properties of a reaction using an AIMD simulation highly depends on the quality of the employed basis set. To this end, we have considered the reactants and products of the water-gas shift reaction (viz., CO, CO2, H2, and H2O) and studied their interaction with the ZnO(10-10) surface using DFT and Born Oppenheimer Molecular Dynamics (BOMD) simulations. By merely changing the quality of the basis set from double zeta (commonly used in most calculations of these systems) to triple zeta, we show that the reaction outcome of an H2O molecule colliding with a ZnO surface pre-covered with carbon monoxide gives qualitatively different results. Furthermore, we show that the calculated adsorption energies can vary by as much as 380 meV (which is an order of magnitude larger than room temperature) by merely changing the basis.