Microcanonical molecular simulations of methane hydrate nucleation and growth: evidence that direct nucleation to sI hydrate is among the multiple nucleation pathways. Issue 14 (6th March 2015)

• Record Type: Journal Article
• Authors: Zhang, Zhengcai; Walsh, Matthew R.; Guo, Guang-Jun
• Is Part Of: Physical chemistry chemical physics. Volume 17:Issue 14(2015)
• Page Start: 8870
• Page End: 8876
• Publication Date: 2015-03-06
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c5cp00098j
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Methane hydrate with a high degree of crystallinity of structure I directly forms via high-precision constant energy MD simulations. Abstract : The results of six high-precision constant energy molecular dynamics (MD) simulations initiated from methane–water systems equilibrated at 80 MPa and 250 K indicate that methane hydrates can nucleate via multiple pathways. Five trajectories nucleate to an amorphous solid. One trajectory nucleates to a structure-I hydrate template with long-range order which spans the simulation box across periodic boundaries despite the presence of several defects. While experimental and simulation data for hydrate nucleation with different time- and length-scales suggest that there may exist multiple pathways for nucleation, including metastable intermediates and the direct formation of the globally-stable phase, this work provides the most compelling evidence that direct formation to the globally stable crystalline phase is one of the multiple pathways available for hydrate nucleation.