Abstract
The relative populations of Cu38 isomers depend to a great extent on the temperature. Density functional theory and nanothermodynamics can be combined to compute the geometrical optimization of isomers and their spectroscopic properties in an approximate manner. In this article, we investigate entropy-driven isomer distributions of Cu38 clusters and the effect of temperature on their IR spectra. An extensive, systematic global search is performed on the potential and free energy surfaces of Cu38 using a two-stage strategy to identify the lowest-energy structure and its low-energy neighbors. The effects of temperature on the populations and IR spectra are considered via Boltzmann factors. The computed IR spectrum of each isomer is multiplied by its corresponding Boltzmann weight at finite temperature. Then, they are summed together to produce a final temperature-dependent, Boltzmann-weighted spectrum. Our results show that the disordered structure dominates at high temperatures and the overall Boltzmann-weighted spectrum is composed of a mixture of spectra from several individual isomers.
Highlights
Nanoclusters are of great interest since they allow us to study the transition from free atoms to bulk condensed systems (Wilcoxon and Abrams, 2006) by analyzing the size-dependent evolution of their properties (Ferrando et al, 2008)
Our findings show that the amorphous structure with C1 symmetry is quite dominant at hot temperatures
Higher-energy structures with significant energy separation between isomers on the potential/free energy surface do not contribute to the overall Infrared spectroscopy (IR) spectrum
Summary
Nanoclusters are of great interest since they allow us to study the transition from free atoms to bulk condensed systems (Wilcoxon and Abrams, 2006) by analyzing the size-dependent evolution of their properties (Ferrando et al, 2008). The present paper uses the statistical formulation of thermodynamics and nanothermodynamics (Li et al, 2007; Li and Truhlar, 2014; Buelna-Garcia et al, 2021; Buelna-Garcia et al, 2021) to compute the thermodynamic properties of the neutral Cu38 cluster, define its putative global minimum at finite temperature, compute the relative populations among the isomers, and the IR spectra as Boltzmann-weighted spectral sums of individual spectra. To compute the probability of the occurrence of one particular Cu38 cluster in a Boltzmann ensemble at thermal equilibrium as a function of temperature, we employed the probability of occurrence (Shortle, 2003; Li et al, 2007; Grimme, 2012; Bhattacharya et al, 2017; Schebarchov et al, 2018; Dzib et al, 2019; Goldsmith et al, 2019; Grigoryan and Springborg, 2019; Mendoza-Wilson et al, 2020; Bhumla et al, 2021; Buelna-Garcia et al, 2021; Buelna-Garcia et al, 2021) given by Eq 5: e−βΔGK. We use the Boltzmann-optics-full-Ader code (BOFA) to compute the occurrence probability and the IR spectra (Buelna-Garcia et al, 2021)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
