Band structures, chemical bonding, and frequency-dependent optical properties of nonlinear optical crystals HgGa2S4 and Hg0.5Cd0.5Ga2S4
Huang Shu-Ping (黄淑萍), Wu Dong-Sheng (吴东升), Li Xiao-Dong (李晓东), Lan You-Zhao (蓝尤钊), Zhang Hao (张浩), Gong Ya-Jing (龚亚京), Li Fei-Fei (李飞飞), Shen Juan (沈娟), Cheng Wen-Dan (程文旦)
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, the Graduate School of the Chinese Academy of Sciences, Fuzhou 350002, China
Abstract Band structures, density of states, chemical bonding properties, and frequency-dependent linear and nonlinear optical properties have been investigated in terms of the density functional theory and an anharmonic oscillator model for HgGa2S4 (HGS) and Hg0.5Cd0.5Ga2S4 (HCGS) crystals. The results obtained show that the top valence bands (VBs) are contributions from Ga--S bonding states and the bottom conduction bands (CBs) are mostly due to Ga--S antibonding states for the HGS crystal, and the top VBs mostly originates from the S-3p states and the bottom CBs are mainly composed of the Ga--S antibonding states for the crystal HCGS. The population analysis shows that both crystals have mixed ionic-covalent bonds. The interactions between Ga and S atoms mostly appear as covalent character, and the Hg--S and Cd--S bonds have substantially ionic characters in HGS and HCGS crystals, respectively. The calculated refractive indices of HGS are compared with the experimental ones, and are found to be in agreement with the experiment data in the low-energy region. It is also found that the band gap of HGS is smaller than that of HCGS, and that the second-order susceptibilities of HGS are larger than those of HCGS.
Received: 21 January 2005
Revised: 25 April 2005
Accepted manuscript online:
PACS:
71.20.-b
(Electron density of states and band structure of crystalline solids)
Fund: Project supported by the National Natural Science Foundation of China (Grant Nos 20373073 and 90201015),the Science Foundation of the Fujian Province, China (Grant NosE0210028 and 2002F010), and the Foundation of State Key Laboratory of Structural Chemist
Cite this article:
Huang Shu-Ping (黄淑萍), Wu Dong-Sheng (吴东升), Li Xiao-Dong (李晓东), Lan You-Zhao (蓝尤钊), Zhang Hao (张浩), Gong Ya-Jing (龚亚京), Li Fei-Fei (李飞飞), Shen Juan (沈娟), Cheng Wen-Dan (程文旦) Band structures, chemical bonding, and frequency-dependent optical properties of nonlinear optical crystals HgGa2S4 and Hg0.5Cd0.5Ga2S4 2005 Chinese Physics 14 1631
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