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    Poly-icosahedral Co-Fe-Pd nanoalloy: Isomerism effect on the structural and magnetic properties from DFT
    (Elsevier, 2022) Yildirim, Hueseyin; Kanbur, Ulvi; Arslan, Haydar
    This study seeks to understand and explain the role of isomerism on the structural and magnetic properties of Co-Fe-Pd nanoalloys. To this end, semiempirical Gupta potential was utilized to identify the first three isomers and the global minimum structures of all compositions, and then these isomers were subject to re-optimization by means of the DFT approach. The structural analysis of Co2FenPd17-n (n = 0-17) nanoalloys revealed that Co atoms prefer locations in the inner sites of the nanoalloys. Fe and Pd atoms occupy the surface for both GM structures and isomers. Our general result shows an increase in the total magnetic moment of the nanoalloys but a decrease in the local magnetic moments of the Co and Fe atoms. Another important result is that the local magnetic moment of the Pd atoms is not zero. These results support the idea that the isomerism effect plays a crucial role in structural and magnetic properties.
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    The structural motif transformations in 71-atom PtAlCu nanoalloys: A combined Atomistic-DFT study
    (Elsevier Science Sa, 2024) Yildirim, Hueseyin; Arslan, Haydar
    The structural motif transformations are vital for the catalytic performance of nanoalloys. A growing body of evidence suggests that Pt-based binary and ternary heterogeneous catalysts are being designed to reduce cost and increase efficiency. The present study aimed to explore the relationship between composition, stress, and the structural families of 71-atom PtnAl52Cu19-n (n = 0-19) nanoalloys, combining Gupta and DFT calculations. We present evidence of the relationship between structural motif transformations, composition and pressure. Also, the segregation phenomena of nanoalloys were confirmed. Our general results are that PtAlCu nanoalloys have three different motifs (Ih, chiral Dh, and daisy) on the surface and 19-atom Dh motif in the inner site, and the daisy motif plays a role in promoting contract or deformation.