(中南大學(xué) 化學(xué)化工學(xué)院，長沙 410083)
摘 要: 用CASTEP程序計(jì)算不同外壓下氫氧化鋁的電子結(jié)構(gòu)與譜學(xué)性質(zhì)，分析外壓對體系能帶結(jié)構(gòu)、態(tài)密度及光學(xué)性質(zhì)的影響。計(jì)算方法選用基于密度泛函理論(DFT)的廣義梯度近似(GGA)方法，用PBE函數(shù)進(jìn)行交換相關(guān)系修正。能帶結(jié)構(gòu)計(jì)算結(jié)果表明，在較高外壓下，如10.0和20.0 GPa，體系的能帶結(jié)構(gòu)較低外壓下變化明顯；體系各k-point點(diǎn)的能隙值隨外壓的增加均呈增大的趨勢，由此也可預(yù)測外壓應(yīng)該對體系的光學(xué)性質(zhì)有一定的影響。態(tài)密度計(jì)算結(jié)果表明，外壓對最低能組態(tài)密度最高峰值影響最明顯，其降低幅度分別達(dá)到15%和20%，價(jià)帶所在能組態(tài)密度最高峰值隨外應(yīng)力增加的減弱幅度相對較小，而外壓對最高能組態(tài)密度最高峰值幾乎沒有影響。光學(xué)計(jì)算結(jié)果表明，外壓對氫氧化鋁的光學(xué)性質(zhì)有一定影響，其反射光譜和吸收光譜有明顯變化，隨外壓的增大，體系的主要反射峰位和吸收峰位對應(yīng)的能量呈變大的趨勢，對應(yīng)的反射系數(shù)和吸收系數(shù)均明顯增大。外壓對介電函數(shù)和導(dǎo)電系數(shù)的影響計(jì)算結(jié)果與對吸收光譜的影響是一致的。
關(guān)鍵字: 氫氧化鋁；電子結(jié)構(gòu)；譜學(xué)性質(zhì)；外壓
（School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China）
Abstract:Electronic structure and optical properties of gibbsite under different external stresses were calculated using CASTEP program. The effects of external stress on bond structure, DOS and optical properties were analyzed. The calculation results indicate that the bond structure under higher external stress, such as 10.0 and 20.0 GPa, is more different than that under lower external stress, and the energy gap of every k-point of systems is increased with augment of external stress, that is to say, the external stress may have some effect on optical properties. The effect of external stress on DOS of the lowest energy group is very distinct, and the reduction is 15% and 20% respectively. The reduction of the energy group in which valence band locates, is less than the lowest energy group relatively, and there is hardly any effect of external stress on the highest energy group. The calculation results of optical properties indicate that with the increase of external stress, the energies of the main reflectivity and absorption peaks are increased, and the corresponding reflectivity and absorption coefficient are increased distinctly. The effect of external stress on dielectric function and conductivity is consistent with the effect on absorption spectrum.
Key words: gibbsite; electronic structure; spectrum property; external stress
