LLM-105晶体形貌分子动力学模拟

Molecular Dynamics Simulation on Crystal Morphology of LLM-105

为了研究在真空和溶剂二甲基亚砜(DMSO)条件下,1-氧-2,6-二氨基-3,5-二硝基吡嗪(LLM-105)的晶体生长形貌,采用分子动力学模拟方法构建了LLM-105在DMSO溶剂中"双层结构"模型,采用平衡形态法和晶体生长法预测了真空中LLM-105的晶体形貌,通过修正附着能分析了DMSO环境下LLM-105的主要控制晶面及其生长速率;通过径向分布函数和晶面结构分析不同晶面与DMSO之间的相互作用;分析了LLM-105粒子的成核能垒。结果表明,LLM-105晶体的4个主要生长晶面为(0 1 1)、(0 2 0)、(1 1 0)和(1 0-1),其中(0 2 0)、(0 1 1)晶面为控制晶面;加入溶剂DMSO后,修正附着能分析得出溶剂中4个晶面附着能远小于真空条件下,说明选择合适的极性溶剂有助于抑制爆发式成核,控制LLM-105的晶体形貌,其中(0 1 1)晶面线性生长速率最小;径向分布函数和晶面结构分析表明,DMSO中H原子与LLM-105(0 1 1)晶面中N原子之间具有较强的氢键和范德华力相互作用;扩散系数分析表明,修正附着能随溶剂扩散系数的增大而减小,溶剂DMSO在(0 1 1)晶面上扩散系数最大,导致该晶面成核能垒高,不容易聚集成核。

To study the crystal growth morphology of 2,6-diamino-3,5-dinitropyrazine-1-oxide（LLM-105）under the condition of vacuum or solvent dimethyl sulfoxide（DMSO）,the double layer structure model of LLM-105 in DMSO solvent was constructed by the molecular dynamics simulation method.The equilibrium morphology method and crystal growth morphology were used to predict the crystal morphology of LLM-105 in vacuum.The main control crystal surface and its growth rate of LLM-105 in DMSO environment were analyzed by modified attachment energy.The interaction between different crystal surfaces and DMSO was analyzed by radial distribution function and surface structure.The nucleation energy barrier of LLM-105 particles was analyzed.The results show that four main growth surfaces of LLM-105 crystal are（0 1 1）,（0 2 0）,（1 1 0）and（1 0-1）,of which,（0 2 0）and（0 1 1）crystal surfaces are the controlled crystal surfaces.After adding solvent DMSO,the modified attachment energy is analyzed to find that the attachment energy of four crystal surfaces in solvent is far smaller than that in the vacuum condition.It is suggested that the appropriate polar solvent can help to suppress explosive nucleation and control the morphology of LLM-105 crystal,of which the linear growth rate of（0 1 1）crystal surface is the smallest.The analyses of radial distribution function and crystal surface structure show that there are strong hydrogen bond and van der Waals interactions between H atoms of DMSO and N atoms of LLM-105（0 1 1）surface.The analysis of diffusion coefficient shows that,the modified attachment energy decreases with the increase of solvent diffusion coefficient,and the maximum diffusion coefficient of solvent DMSO on（0 1 1）crystal surface is observed,which results in the high nucleation barrier of（0 1 1）surface and not easy to aggregate nucleation.