The role of tagging atoms on the thermal stability and vibrational behavior of Nb9 clusters

Extensive comparative study of density functional theory calculations dedicated to analyzed the influence of the so-called tagging atoms on the thermal stability and vibrational behavior of small Nb9—Arn (n = 1–4) clusters are presented. We consider two-hybrid functional (HSEH1PBE and CAM-B3LYP) models to obtain minimum energy structures and, the relative concentrations of several Ar complexes configurations when varying the temperature of the system are determined by constructing partition functions and enthalpies. Under these considerations, it was found that the coexistence of two different isomers of the Nb9 clusters in a sample is highly probable. Additionally, some interesting points can be highlighted, for instance, i) the different hybrid exchange-correlation functionals modify the proportions of mole fractions in all cases, ii) the weighted average of the IR spectra proposed by the mole fractions have better agreement with the experimental data, iii) tagging atoms can induce significant variations in the infrared spectra, such variations consist mainly of noticeable changes in the relative intensity of the active infrared frequencies. In conclusion, even if the percentage of isomers shown in the mole fractions changes as a function of the hybrid exchange-correlation functional, the influence of tagging atoms makes some changes in the calculation of the partition function and in the simulated IR spectra. For this reason, it is suggested to include tagging atoms in theoretical calculations to have a better understanding of the experimental data. •Theoretical study analyzing the effect of the argon atom on thermal stability.•Influence of argon atoms on the infrared spectrum of Nb9 clusters.•The number of argon atoms affects the proportion of mole fractions.•Coexistence between Nb9 isomers is highly plausible.•Weighted average of the IR spectra of Nb9—Arn (n = 1–4) induced by the mole fractions.