Substitutional and orientational disorder in organic crystals: a symmetry-adapted ensemble model

被引：51

作者：

Habgood, Matthew ^{[1
]}

Grau-Crespo, Ricardo ^{[1
]}

Price, Sarah L. ^{[1
]}

机构：

[1] UCL, Dept Chem, London WC1H 0AJ, England

来源：

PHYSICAL CHEMISTRY CHEMICAL PHYSICS | 2011年 / 13卷 / 20期

基金：

英国工程与自然科学研究理事会;

关键词：

POTENTIAL-FUNCTION MODELS; MINERAL SOLID-SOLUTIONS; RAY-POWDER-DIFFRACTION; X-RAY; DIFFUSE-SCATTERING; DISTRIBUTED MULTIPOLE; STRUCTURE PREDICTION; COMPUTER-SIMULATION; ENERGY CALCULATIONS; MOLECULAR-CRYSTAL;

D O I：

10.1039/c1cp20249a

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

Modelling of disorder in organic crystals is highly desirable since it would allow thermodynamic stabilities and other disorder-sensitive properties to be estimated for such systems. Two disordered organic molecular systems are modeled using a symmetry-adapted ensemble approach, in which the disordered system is treated as an ensemble of the configurations of a supercell with respect to substitution of one disorder component for another. Computation time is kept manageable by performing calculations only on the symmetrically inequivalent configurations. Calculations are presented on a substitutionally disordered system, the dichloro/dibromobenzene solid solution, and on an orientationally disordered system, eniluracil, and the resultant free energies, disorder patterns, and system properties are discussed. The results are found to be in agreement with experiment, when some physically implausible configurations are removed from the ensemble average for eniluracil, highlighting the dangers of a completely automated approach to organic crystal thermodynamics which ignores the barriers to equilibration once the crystal has been formed.

引用

页码：9590 / 9600

页数：11

共 69 条

[1] Bulk and surface simulation studies of La1-xCaxMnO3 [J].