Computational Study Of Structural And Electronic Properties Of Metal Clusters

In recent years,the scientific community all over the world has devoted considerable efforts to study the atomic structures and electronic properties of clusters.A clear understanding of the structural stability and electronic structure of clusters is critical for various applications such as catalysis,nano-plasmonics,meta-materials,sensing,medicine,etc.Despite the remarkable achievements,there are still plenty of open questions to be addressed,especially regarding the structure-property relationship under realistic conditions.In fact,even the simplest electronic properties such as the ionization potentials（IPs）and energy gaps of many types of clusters,are not readily available from experiments,and computational results based on density functional theory heavily depend on the employed functionals.In the present work,focusing on small metal（including alkali,alkali earth,aluminum,and zinc）clusters,we have performed systematic benchmark studies on their geometrical and electronic structures using a "two-step" approach.In the first step,we combine the structure prediction method and first-principles calculations to determine globally stable and low-lying metastable structures;in the second step,we employ the G₀W₀ approximation within the many-body perturbation theory to investigate the electronic properties of these clusters,including the ionization energies,electron affinities,and energy gaps.Based on these results,we perform an in-depth analysis of the relationship between geometrical structures and electronic properties of several groups of metal clusters.In this work,not only the globally most stable isomer of each cluster size but also the low-lying metastable ones are studied because these can also be relevant under finite temperatures and realistic conditions.Van der Waals interactions are also considered,and their influence on the structures of the metal clusters is analyzed.Through this work,we have identified novel ground-state isomer structures of Be₁₄,Mg₁₄,and Mg₁₆ clusters.Furthermore,we report the state-of-the-art high-precision all-electron G₀W₀ results for several series of clusters,and for some of them,the results from G₀W₀ plus the second-order screened exchange（SOSEX）correction are also included.We find that the second differences in the binding energies and ionization energies of the metal clusters are intimately correlated,displaying a "maximal hardness principle".Moreover,our study reveals that the size evolution of the IEs and EAs of different series of clusters show different qualitative behaviors.For example,the size evolution of the IPs of alkali metal clusters displays a pronounced even-odd oscillation behavior,whereas this does not hold for alkali earth and aluminum clusters.This benchmark study provides a solid basis for further investigations and improving methods to accelerate cluster and material science research.Our work also indicates that the combination of ground-state DFT,unbiased structural search algorithm,and the Green-function based quasiparticle method leads to a powerful approach to systematically investigating the properties of clusters...