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arXiv 1606.08355cond-mat.mtrl-scicond-mat.mes-hallphysics.atm-clusphysics.comp-ph
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化学计量比WS2纳米团簇稳定异构体的第一性原理结构搜索

First-principles structure search for the stable isomers of stoichiometric WS2 nano-clusters

Roohollah Hafizi, S. Javad Hashemifar, Mojtaba Alaei, MohammadReza Jangrouei, Hadi Akbarzadeh

摘要:

在本文中,我们采用进化算法与全势能密度泛函理论(DFT)计算进行全面的搜索化学计量(WS 2)n纳米团簇(n=1-9)的稳定结构,在三个不同的交换相关泛函。我们的研究结果表明,n=3,5,8是WS 2纳米团簇的低温幻尺寸的可能候选者,而在600开尔文以上的温度下,n=5和7在所研究的系统中表现出更高的相对稳定性。采用半定域PBE和BLYP泛函、杂化B3 LYP泛函、多体DFT+GW方法和含时DFT方法计算了最低能量异构体的电子性质和能隙.用力常数法计算了最低位异构体的振动光谱,并计算了团簇的红外光谱和热自由能。采用含时密度泛函方法计算了WS 2纳米团簇最低能量异构体的全吸收光谱和光学带隙。

英文摘要:

In this paper, we employ evolutionary algorithm along with the full-potential density functional theory (DFT) computations to perform a comprehensive search for the stable structures of stoichiometric (WS2)n nano-clusters (n=1-9), within three different exchange-correlation functionals. Our results suggest that n=3, 5, 8 are possible candidates for the low temperature magic sizes of WS2 nano-clusters while at temperatures above 600 Kelvin, n=5 and 7 exhibit higher relative stability among the studied systems. The electronic properties and energy gap of the lowest energy isomers were computed within several schemes, including semilocal PBE and BLYP functionals, hybrid B3LYP functional, many body based DFT+GW approach, and time dependent DFT calculations. Vibrational spectra of the lowest lying isomers, computed by the force constant method, are used to address IR spectra and thermal free energy of the clusters. Time dependent density functional calculation in real time domain is applied to determine the full absorption spectra and optical gap of the lowest energy isomers of the WS2 nano-clusters.

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