(218h) Modeling Self-Assembly of Metal-Organic Frameworks with Enhanced Sampling Techniques
- Conference: AIChE Annual Meeting
- Year: 2017
- Proceeding: 2017 AIChE Annual Meeting
- Group: Computational Molecular Science and Engineering Forum
Monday, October 30, 2017 - 5:00pm-5:15pm
We employ a combination of enhanced sampling techniques to study MOF self-assembly for different scenarios and system sizes. We model MOF-5 with an atomistic model as either a discrete unit cell or four unit cells in explicit solvent. To validate the model, we perform replica exchange with solute scaling (REST2) simulations and calculate the free energy profile using the average distance and average angle between nodes as collective variables. The free energy minima observed in these systems are close to the values in the experimental unit cell, therefore validating that the chosen model represents at least a metastable state.
To model self-assembly, we perform finite temperature string (FTS) method calculations using the average distance and angle between nodes and the total coordination between nodes and linkers. The process was modeled for both single and four unit cells systems from two starting points: fully disassembled and amorphous. The self-assembly starting from the disassembled state was found to be downhill in free energy for both the single unit cell and four unit cells systems. In contrast, the self-assembly starting from the amorphous state reveals energetic barriers on the way to the final MOF structure. Finally, we discuss the mechanism of self-assembly of MOF-5 for the scenarios and system sizes considered.