Title: The structural, mechanical, electronic, optical and thermodynamic properties of t-X₃As₄ (X = Si, Ge and Sn) by first-principles calculations
Author(s):

	R. Yang (School of Physics and Optoelectronic Engineering, Xidian University, Xi'an, Shaanxi 710071, PR China) ,
	Y. Ma (School of Physics and Optoelectronic Engineering, Xidian University, Xi'an, Shaanxi 710071, PR China) ,
	Q. Wei (School of Physics and Optoelectronic Engineering, Xidian University, Xi'an, Shaanxi 710071, PR China) ,
	D. Zhang (National Supercomputing Center in Shenzhen, Shenzhen 518055, PR China) ,
	Y. Zhou (Leihua Electronic and Technology Research Institute, Aviation Industry Corporation of China, Wuxi, Jiangsu 214063, PR China)

The structural, mechanical, electronic, optical and thermodynamic properties of the t-X₃As₄ (X = Si, Ge and Sn) with tetragonal structure have been investigated by first principles calculations. Our calculated results show that these compounds are mechanically and dynamically stable. By the study of elastic anisotropy, it is found that the anisotropic of the t-Sn₃As₄ is stronger than that of t-Si₃As₄ and t-Ge₃As₄. The band structures and density of states show that the t-X₃As₄ (Si, Ge and Sn) are semiconductors with narrow band gaps. Based on the analyses of electron density difference, in t-X₃As₄ As atoms get electrons, X atoms lose electrons. The calculated static dielectric constants, ε₁(0), are 15.5, 20.0 and 15.1 eV for t-X₃As₄ (X = Si, Ge and Sn), respectively. The Dulong-Petit limit of t-X₃As₄ is about 10 J mol^-1K^-1. The thermodynamic stability successively decreases from t-Si₃As₄ to t-Ge₃As₄ to t-Sn₃As₄.

Key words: t-X₃As₄, mechanical properties, optoelectronic properties, thermodynamic properties, first-principles calculations
PACS: 61.82.Bg, 62.20.dc, 71.20.Be, 71.15.Mb

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