Surface-Mediated Nucleation in the Solid-State Polymorph Transformation of Terephthalic Acid

Abstract

A molecular mechanism for nucleation for the solid-state polymorph transformation of terephthalic acid is presented. New methods recently developed in our group, aimless shooting and likelihood maximization, are employed to construct a model for the reaction coordinate for the two system sizes studied. The reaction coordinate approximation is validated using the committor probability analysis. The transformation proceeds via a localized, elongated nucleus along the crystal edge formed by fluctuations in the supramolecular synthons, suggesting a nucleation and growth mechanism in the macroscopic system.

Nonlinear reaction coordinate analysis in the reweighted path ensemble

“…In this paper, we address these two points simultaneously by allowing for a nonlinear description of the reaction coordinate that completely describes the reaction from the initial to the final state. Note that by nonlinearity, we mean not the nonlinearity of the collective variables themselves ͑previous works often use nonlinear collective variables such as angles 12,17,18 ͒, but the nonlinear correlation between these collective variables describing the entire reaction. This nonlinear description is based on ideas from the string method as developed by Vanden-Eijnden and co-workers.…”

Crystal Shape Engineering

“…42 Acetic acid aggregation in carbon tetrachloride solution was found to proceed through dimer formation to oligomers to hydrogen bonded micelles. 43 New simulation techniques such as reaction coordinate calculation and transition path sampling 44,45 may soon allow for a more complete study of small molecule nucleation from solution.…”

Transition Path Sampling and Other Advanced Simulation Techniques for Rare Events

“…For this reason, nucleation is a rare event and requires special computational techniques [194]. Nucleation processes that have been studied with transition path sampling include magnetization reversal in the Ising-model [195], pressure induced phase transitions in semiconductor nanoclusters [180], the freezing of Lennard-Jonesium [196], phase separation and crystallization from the melt [197], the solid-solid transition of terephtalic acid [198], the liquid-vapor transition of methane [199], the wurtzite to rocksalt transition in bulk CdSe [200], the boiling of water [201], pressure induced transitions of alkali halides [202,203,204,205,206,207], and crystallization from solution [208].…”

“…A detailed statistical analysis of the computation of committor histograms has been carried out by Peters [267]. Initially introduced to study ionic dissociation in water [23], committor distribution analysis was subsequently applied to elucidate the mechanism of various complex reactions [24,26,27,195,196,198,268].…”

“…[272]. Maximum Likelihood estimation has been used to identify the mechanistic details of nucleation in the Ising model [27] and of structural solid-solid transitions of terephtalic acid [198].…”