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通过构建晶体表面-KDP分子界面吸附结构模型,采用分子动力学和密度泛函计算方法研究KDP分子在(001)和(010)面吸附的物理化学过程,考察了温度对物理吸附行为的影响.研究表明:KDP晶体表面的吸附过程和生长习性主要由化学吸附主导,化学吸附能的计算表明[K-O_8]基元在(001)界面的结合能是(010)界面结合能的2.86倍;在饱和温度附近,[H_2PO_4]ˉ阴离子在KDP界面的物理结合能随温度的变化呈现振荡特征,溶液中有较多的离子团簇形成,溶液变得很不稳定;当温度从323 K降低至308 K时,水分子在界面的结合能总体呈下降趋势,而KDP分子在界面的吸附能总体呈上升趋势,脱水过程是水分子和[H_2PO_4]ˉ阴离子在固液界面边界层竞争吸附的结果.研究结果对确足晶体生长界面动力学过程发展和完善晶体生长理论有重要意义.
KDP molecules were adsorbed on the (001) and (010) surfaces by means of molecular dynamics and density functional calculations. The effects of temperature on the physical adsorption behavior were investigated. The results show that the adsorption process and growth habit of KDP crystal are mainly dominated by chemisorption. Calculations of chemisorption energy indicate that the binding energy of [K-O_8] element at the (001) interface is 2.86 times that of the (010) In the vicinity of the saturation temperature, the physical binding energy of [H 2 PO 4] ˉ anion at the KDP interface shows oscillatory characteristics with the temperature changing. There are more ionic clusters in the solution and the solution becomes unstable. When the temperature decreases from 323 K to At 308 K, the binding energy of water molecules at the interface tends to decrease, while the adsorption of KDP at the interface shows an overall upward trend. The dehydration process is the result of competitive adsorption of water molecules and [H 2 PO 4] anions at the boundary layer of the solid-liquid interface The results of this study are of great importance to the development of the kinetic process of crystal growth interface and the theory of crystal growth.