非晶态SrTiO_3结构特征的分子动力学模拟

Structure characters of non-crystalline SrTiO_3 by molecular dynamics simulation

本文采用分子动力学方法,势函数为PIM（Partial Ionic Model）势,模拟了SrTiO3的熔化过程,将熔化的SrTiO3快速冷却到室温以获得非晶态.通过熔化过程中体系体积的突变,确定熔点为2420K,仅比实验值高1.68%,很好的反映了SrTiO3的熔化过程;非晶态基本保留了液态的结构特征.ABO3型材料中,Ti-O键起到关键的作用.本文首次利用分子动力学模拟得到了与实验值相符合得很好的非晶态SrTiO3结构.非晶态下,Ti-O键键长为1.845（A）,键角主要分布在95.5～122.5°,平均配位数为4.92.非晶态中的Ti-O配位以5配位为主,约占80％,同时包含少量的4、6配位.

Molecular dynamics method with the interaction model of P IM（Partial Ionic Model） was adopted to simulating the melting and quenching process of SrTiO3. From the sudden increasing of the system volume, the melting point of SrTiO3 was estimated at 2420 K, only-1.68 % higher than that of experiment value, which indicates that the method adapted by this paper eorrectly represented the melting process of SrTiO3. The noncrystalline SrTiO3 solid is obtained from quenching of the liquid to room temperature. The non-crystalline has the basic characters of structure of the liquid state. In the ABO3. materials, the key structure is the that of Ti-O. The result of this simulation shows that in non-crystalline state, the Ti-O bend length is 1.845 A, and the bend angle main distributed in 95.5- 122.5°. The average coordination number is 4.92. In the coordination chemistry, about 80 % of Ti is surrounded by 5 oxygen, which agree well with the experiment value. At the same time, there are some 4 and 6 coordination exist in the system. The eonclusion can be drew out that the non-crystalline was eorrectly reproduced first time by this simulation.