Vibrational frequency and vibrational entropy computations were carried out with the harmonic oscillator (HO) approximation. Vibrational frequencies of CO * were calculated from a Hessian matrix using a finite-difference method with a displacement magnitude of 0.01 Å via ASE. The surface atoms were fixed during the vibrational analysis, which is consistently done in the field. However, new methods are emerging that account for the impact of surface phonons on adsorption enthalpies and vibrational modes .