New global minimum conformers for the  Pt19 and Pt20 clusters. Low symmetric species featuring different active sites

Abstract The study of Pt clusters and nanoparticles is a prominent area of research due to their ex- tensive range of potential technological applications, particularly in the field of catalysis. The electronic properties of Pt clusters that result in optimal catalytic performance at the nanoscale are significantly influenced by their size and structure. In this report, we sought to evaluate the lowest-energy candidates for Pt18−20 species via Density Functional Theory, identifying more favorable conformers than those previously documented in the literature. New low-symmetry conformers for the Pt19 and Pt20 systems were identified, which are 3.0 and 1.0 kcal/mol more stable, respectively, than previously reported structures (Phys. Rev. B: Condens. Matter Mater. Phys., 2008, 77, 205418). Furthermore, we examined the impact of diverse DFT ap- proximations, including GGA (PBE), meta-GGA (TPSS, M06-L), hybrid (PBE0 and PBEh), meta-GGA hybrid (TPSSh), and range-separated hybrid (ωB97x) functionals. Additionally, we evaluated the quality of the employed basis sets in determining the relative energies and structures of the investigated clusters. Our findings indicate that a correct energy ordering for the different isomers examined can only be achieved by employing density functional approximations that incorporate moderate levels of exact Hartree-Fock exchange, in conjunction with the utilization of basis sets of at least quadruple-zeta quality. The resulting structures are asymmetric, with different active sites as evidenced by the analysis of the sigma holes on the electrostatic potential surface. This observation suggests a potential correlation between the electronic structure and the catalytic properties of these Pt clusters, which merits further investigation. We expect that this work will prove to be a valuable reference point for future electronic structure reports dealing with the precise ordering of structures in the determination of global minima of metallic clusters.