Phase Diagram of ZIF-4 Computed via Well-tempered Metadynamics

Abstract

Well-tempered metadynamics simulations are employed to explore the phase diagram of ZIF-4, a porous crystalline metal-organic framework of industrial relevance. Despite the vast amount of experimental efforts, the phase diagram that includes ZIF-4 and its related polymorphs has not yet been fully determined. For example, the crystalline phase called ZIF-4-cp is not experimentally observed when high pressure ramps are applied. Our simulations shed light into the phase diagram topology and allow us to further look into the collective degrees of freedom that drive the phase transitions in the T=150-450 K and P=0-200 MPa region. The porous ZIF-4 phase transforms into ZIF-4-cp through pore closure, while the latter has a phase transition at higher pressures regimes to ZIF-4-cp-II, a transformation which involves subtle changes in swing dihedral angles.

28 pages, 5 figures, 2 tables, supporting information included with 3 additional figures

References in corpus (3)

• Well-Tempered Metadynamics: A Smoothly Converging and Tunable Free-Energy Method
• Computer Simulation of the Early Stages of Self-Assembly and Thermal Decomposition of ZIF-8
• Microscopic Mechanism of the Thermal Amorphization of ZIF-4 and Melting of ZIF-zni Revealed via Molecular Dynamics and Machine Learning Techniques

Cited by in corpus (4)

• Thermodynamic Insights into the Self-assembly of Zeolitic Imidazolate Frameworks from Computer Simulations
• Systematic Study of Machine Learning Classification Algorithms of Zeolitic Imidazolate Framework Polymorphs
• Reactive Coarse Grained Force Field for Metal-Organic Frameworks applied to Modeling ZIF-8 Self-Assembly
• Active learning potentials for first-principles phase diagrams using replica-exchange nested sampling