Practical quantum mechanics-based fragment methods for predicting molecular crystal properties

• Published in: Physical chemistry chemical physics : PCCP 2012-06, Vol.14 (21), p.7578-759
• Main Authors: Wen, Shuhao, Nanda, Kaushik, Huang, Yuanhang, Beran, Gregory J. O
• Format: Article
• Language: English
• Subjects: Chemistry; Condensing; Coupling (molecular); Crystal lattices; Crystals; Density; Exact sciences and technology; Fragmentation; General and physical chemistry; Lattice parameters; Mathematical models
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c2cp23949c

Significant advances in fragment-based electronic structure methods have created a real alternative to force-field and density functional techniques in condensed-phase problems such as molecular crystals. This perspective article highlights some of the important challenges in modeling molecular crystals and discusses techniques for addressing them. First, we survey recent developments in fragment-based methods for molecular crystals. Second, we use examples from our own recent research on a fragment-based QM/MM method, the hybrid many-body interaction (HMBI) model, to analyze the physical requirements for a practical and effective molecular crystal model chemistry. We demonstrate that it is possible to predict molecular crystal lattice energies to within a couple kJ mol −1 and lattice parameters to within a few percent in small-molecule crystals. Fragment methods provide a systematically improvable approach to making predictions in the condensed phase, which is critical to making robust predictions regarding the subtle energy differences found in molecular crystals. Fragment-based electronic structure methods are creating new, computationally affordable opportunities for accurately modeling molecular crystal structures and properties.