Nucleation rate analysis of methane hydrate from molecular dynamics simulations

Area of Science:

• Thermodynamics
• Materials Science
• Computational Chemistry

Background:

• Clathrate hydrates are complex crystalline solids formed from water and gas.
• Understanding clathrate hydrate nucleation is crucial for their applications.
• Molecular dynamics (MD) simulations offer molecular-level insights into nucleation processes.

Purpose of the Study:

• To evaluate the applicability of mean first-passage time (MFPT) and survival probability (SP) methods for analyzing clathrate hydrate nucleation.
• To adapt and apply these methods to study methane clathrate hydrate nucleation using MD simulations.
• To determine the nucleation rate and critical nucleus size of methane clathrate hydrates.

Main Methods:

• Utilized molecular dynamics (MD) simulations to generate data for methane clathrate hydrate nucleation at 255 K and 50 MPa.
• Applied and adapted the mean first-passage time (MFPT) method, incorporating maximum likelihood estimation and a growth effect term.
• Employed the survival probability (SP) method for comparative analysis.

Main Results:

• Nucleation rates calculated by MFPT and SP methods showed excellent agreement, within 5% of each other.
• The critical nucleus size estimated by the MFPT method was 50% larger than values from more computationally intensive methods.
• The adapted MFPT and SP methods proved effective for analyzing clathrate hydrate nucleation.

Conclusions:

• MFPT and SP methods, when adapted, are viable and efficient tools for studying clathrate hydrate nucleation.
• These computational methods provide reliable estimates for nucleation rates and critical nucleus sizes.
• The approach can be extended to investigate the nucleation of other types of clathrate hydrates.