The vibrational frequencies obtained from DFT were used in partition functions for harmonic oscillators, from which the vibrational entropy was obtained, both for the low-coverage limit and for the coverage-dependent correction. Coverage influences the entropy of adsorbed CO on Pt(111) and Co(0001) derived from the structures of the global minimum method similarly (see Figure ). First, the entropy increases, which is a consequence of the decreasing low-frequency tilting modes up to a coverage of 4/9 ML for Pt(111) and 1/3 ML for Co(0001). The entropy decreases by 10 J mol -1 K -1 on Pt(111) at 1 ML CO coverage, whereas on Co(0001) the entropy decreases by