Pd8 Cluster: Too Small to Melt? A BOMD Study

Analila Luna-Valenzuela, Jesús N. Pedroza-Montero, Andreas M. Köster, Patrizia Calaminici, Luis E. Gálvez-González, Alvaro Posada-Amarillas*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The question of whether a solid-liquid phase transition occurs in small clusters poses a fundamental challenge. In this study, we attempt to elucidate this phenomenon through a thorough examination of the thermal behavior and structural stability of Pd8 clusters employing ab initio simulations. Initially, a systematic global search is carried out to identify the various isomers of the Pd8 cluster. This is accomplished by employing an ab initio basin-hopping algorithm and using the PBE/SDD scheme integrated in the Gaussian code. The resulting isomers are further refined through reoptimization using the deMon2k package. To ensure the structural firmness of the lowest-energy isomer, we calculated normal modes. The structural stability as a function of temperature is analyzed through the Born-Oppenheimer molecular dynamics (BOMD) approach. Multiple BOMD trajectories at distinct simulated temperatures are examined with data clustering analysis to determine cluster isomers. This analysis establishes a connection between the potential energy landscape and the simulated temperature. To address the question of cluster melting, canonical parallel-tempering BOMD runs are performed and analyzed with the multiple-histogram method. A broad maximum in the heat capacity curve indicates a melting transition between 500 and 600 K. To further examine this transition, the mean-squared displacement and the pair-distance distribution function are calculated. The results of these calculations confirm the existence of a solid-liquid phase transition, as indicated by the heat capacity curve.

Original languageEnglish
Pages (from-to)572-580
Number of pages9
JournalJournal of Physical Chemistry A
Volume128
Issue number3
DOIs
StatePublished - 25 Jan 2024

Bibliographical note

Publisher Copyright:
© 2024 American Chemical Society

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