Size and Temperature Dependent Shapes of Copper Nanocrystals using Replica-Exchange Molecular Dynamics Simulations
Restricted (Penn State Only)
Author:
Khan, Mohd Ahmed
Graduate Program:
Chemical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
April 25, 2023
Committee Members:
Seong Kim, Professor in Charge/Director of Graduate Studies Kristen Fichthorn, Thesis Advisor/Co-Advisor Ali Borhan, Committee Member Ismaila Dabo, Committee Member
Keywords:
copper replica exchange molecular dynamics common neighbor analysis embedded atom method
Abstract:
Comprehending the development and alterations of metal nanocrystals in colloidal form as they assume different shapes holds great importance both in terms of fundamental scientific understanding and technological applications. As the connection between the shapes of nanocrystals and their properties for various applications is well-established, research exploring the potential applications of metal nanocrystals is experiencing substantial growth. While numerous theoretical studies have investigated the energetically favorable shapes of small clusters with seed-like dimensions in a vacuum, limited research has thoroughly examined the influence of temperature on these shapes. To investigate the temperature-dependent shapes of copper (Cu) nanocrystals within the size range of 100 to 200 atoms, we employ replica exchange molecular dynamics (REMD) simulations with EAM potential. We utilize common-neighbor analysis (CNA) to categorize the shapes of the nanocrystals into decahedra (Dh), icosahedra (Ih), intermediate structures that exhibit features of both Dh and Ih (Dh-Ih), single-crystal with face-centered cubic (FCC) symmetry, and single-crystal with stacking faults (SCSF). In this process, we found interesting structures which were earlier regarded as unclassified. In summary, we have developed a computational methodology to determine the equilibrium structures of nanoclusters within a temperature range spanning from 300 K up to the melting point.
