锡砷化合物真空热分解的从头算分子动力学模拟

Ab Initio Molecular Dynamics Study of Thermal Decomposition of Arsenic-Tin Compounds in Vacuum

为研究锡砷化合物真空下热分解的机理,对Sn_4As_3和SnAs化合物进行真空条件下热分解的热力学计算,得到它们30 Pa的条件下开始发生反应的温度。采用基于密度泛函理论的平面波赝势法计算得到Sn_4As_3和SnAs的稳定结构,在此基础上用从头算分子动力学的方法模拟了它们在1463 K,30 Pa和1373 K,30 Pa条件下的热分解过程,并计算了Sn_4As_3和SnAs(100)面的热分解。过程计算结果表明,在模拟条件下超胞内砷的脱除可能分步进行,并且更倾向于以As_2的形式分解。表面的Sn-As键比晶胞内部更加容易分离。

The Gibbs free energy of vacuum thermal decomposition of arsenic-tin compounds,rich in tin-refining slag,was calculated in thermodynamics to estimate the decomposition starting temperature at 30 Pa.The stable structures of the Sn4As3 and SnAs compounds were numerically calculated in the plane-wave pseudopotential method based on the density functional theory;and the thermal decomposition,particularly on Sn4As3（100） and SnAs（100） surfaces,under the conditions：a pressure of 30 Pa and temperatures of 1463 and 1373 K,was theoretically simulated in ab initio molecular dynamics calculation.The simulated results show that the arsenic can be indirectly removed step by step,possibly in the form of As2.In addition,the Sn-As bond on the surfaces was found to break more easily than that in the bulk.We suggest that the simulated results be of some basic and technological interest in vacuum metallurgy.