Density Functional Study on Compounds to Accelerate the Electron Capture Decay of ⁷Be.

Area of Science:

• Nuclear Chemistry
• Materials Science
• Computational Chemistry

Background:

• Electron capture (EC) decay rates are inversely proportional to electron density at the nucleus (ρ(0)).
• Modifying chemical environments can alter EC decay rates.
• Previous studies showed a slight half-life reduction for ⁷Be in C₆₀, but the insertion method was impractical.

Purpose of the Study:

• To elucidate the mechanism of ρ(0) changes in various beryllium (Be) compounds.
• To propose novel, practical systems for accelerating EC decay (increasing ρ(0)).
• To identify systems easier to generate than Be encapsulated in C₆₀.

Main Methods:

• Density functional calculations were employed to analyze ρ(0) in different Be compounds.
• Investigated Be encapsulated in fullerenes (C₂₀-C₁₈₀).
• Proposed and theoretically evaluated Be-encapsulated rare gas solids under high pressure.

Main Results:

• Typical Be compounds showed decreased ρ(0) due to electron donation.
• Be encapsulated in C₅₀ fullerene yielded the largest ρ(0) increase among fullerenes, comparable to C₆₀.
• Be-encapsulated rare gas solids demonstrated a significant ρ(0) increase (2-10%) dependent on lattice constant, achievable under high pressure.

Conclusions:

• Be-encapsulated rare gas solids represent a promising new system for accelerating EC decay due to significant ρ(0) enhancement.
• These systems are potentially more practical to generate than Be in C₆₀.
• Further research into high-pressure synthesis of these materials is warranted.