Schneider Elia, Vogt Leslie, Tuckerman Mark E
Department of Chemistry, New York University, New York, NY 10003, USA.
Acta Crystallogr B Struct Sci Cryst Eng Mater. 2016 Aug 1;72(Pt 4):542-50. doi: 10.1107/S2052520616007873.
Prediction and exploration of possible polymorphism in organic crystal compounds are of great importance for industries ranging from organic electronics to pharmaceuticals to high-energy materials. Here we apply our crystal structure prediction procedure and the enhanced molecular dynamics based sampling approach called the Crystal-Adiabatic Free Energy Dynamics (Crystal-AFED) method to benzene and naphthalene. Crystal-AFED allows the free energy landscape of structures to be explored efficiently at any desired temperature and pressure. For each system, we successfully predict the most stable crystal structures at atmospheric pressure and explore the relative Gibbs free energies of predicted polymorphs at high pressures. Using Crystal-AFED sampling, we find that mixed structures, which typically cannot be discovered by standard crystal structure prediction methods, are prevalent in the solid forms of these compounds at high pressure.
预测和探索有机晶体化合物中可能存在的多晶型对于从有机电子学、制药到高能材料等一系列行业都至关重要。在此，我们将我们的晶体结构预测程序以及基于增强分子动力学的采样方法——晶体绝热自由能动力学（Crystal-AFED）方法应用于苯和萘。Crystal-AFED能够在任何所需的温度和压力下有效地探索结构的自由能态势。对于每个体系，我们成功预测了大气压下最稳定的晶体结构，并探索了高压下预测多晶型物的相对吉布斯自由能。使用Crystal-AFED采样，我们发现混合结构在这些化合物高压下的固态形式中普遍存在，而混合结构通常无法通过标准晶体结构预测方法发现。
