Molecular crystal global phase diagrams. II. Reference lattices

Area of Science:

• Crystallography and Materials Science
• Computational Chemistry
• Chemical Physics

Background:

• Previous work established a method for constructing global phase diagrams (GPDs) for molecular crystals based on intermolecular potential parameters.
• A face-centered-cubic lattice was previously used as an arbitrary reference state.
• Understanding the diversity of crystal structures is crucial for developing comprehensive GPDs.

Purpose of the Study:

• To classify experimental crystal structures of molecules with tetrahedral point group symmetry.
• To determine the fraction of these structures amenable to inclusion in GPDs.
• To identify the number of reference lattices required to encompass the observed structures.

Main Methods:

• Classification of experimental crystal structures based on molecular point group symmetry (specifically T(d)).
• Analysis of the relationship between crystal structure and intermolecular potential parameters.
• Determination of the minimum number of reference lattices needed to represent the structural landscape.

Main Results:

• Sixty percent of crystal structures composed of tetrahedral molecules were found to be amenable to inclusion in GPDs.
• Eight reference lattices were determined to be sufficient to span the observed crystal structures.
• These findings suggest a systematic approach to representing diverse molecular crystal structures.

Conclusions:

• A significant portion of tetrahedral molecular crystal structures can be represented within a GPD framework.
• A defined set of reference lattices can effectively cover the structural diversity observed for these molecules.
• Similar methodologies are expected to yield comparable results for other cubic point group molecules.