A Systematic Protocol for Benchmarking Guest-Host Interactions by First-Principles Computations: Capturing CO₂ in...

Area of Science:

• Computational Chemistry
• Materials Science
• Environmental Science

Background:

• Carbon dioxide (CO₂) clathrate hydrates are investigated for greenhouse gas capture and storage.
• A complete molecular-level understanding of CO₂ hydrate formation and properties is lacking.
• Accurate molecular modeling is crucial but computationally intensive for predicting hydrate properties.

Purpose of the Study:

• To investigate the nature of guest-host interactions in CO₂ clathrate hydrates (sI, sII, sH cages).
• To assess the accuracy of different computational methods for modeling CO₂ @H₂ O interactions.
• To determine the energetic favorability and optimal orientation of CO₂ encapsulation in clathrate cages.

Main Methods:

• Performed first-principles calculations for CO₂ in sI, sII, and sH clathrate cages.
• Studied various density functionals and quantum approaches, including pairwise CO₂ @H₂ O potentials.
• Generated benchmark energies using distance-dependent datasets and proposed a protocol for assessing computational methods.

Main Results:

• Dispersion interactions significantly contribute to the stabilization energy of CO₂ within clathrate cages.
• Encapsulation of CO₂ into guest-free clathrate cages is consistently energetically favorable.
• Analyzed CO₂ orientation within cages and discussed the accuracy of computational approaches for guest-host interactions.

Conclusions:

• First-principles calculations provide critical insights into CO₂ clathrate hydrate interactions.
• Dispersion forces play a vital role in the stability of CO₂ within clathrate structures.
• The findings guide the selection of accurate computational methods for future multiscale simulations of CO₂ capture.