Isotope shift in the electron affinity of lithium

Area of Science:

• Atomic Physics
• Quantum Chemistry
• Computational Chemistry

Background:

• Electron affinity (EA) is a fundamental atomic property.
• Accurate theoretical calculations are crucial for understanding atomic structure and interactions.
• Previous calculations often relied on the Born-Oppenheimer approximation, limiting accuracy.

Purpose of the Study:

• To perform highly accurate electron affinity calculations for lithium-6 and lithium-7 isotopes.
• To investigate the effects of nuclear motion by not assuming the Born-Oppenheimer approximation.
• To compute relativistic and quantum electrodynamics corrections for enhanced precision.

Main Methods:

• Utilized explicitly correlated Gaussian functions for calculations.
• Employed a variational approach that incorporates nuclear motion.
• Included leading relativistic and quantum electrodynamics corrections.

Main Results:

• Achieved the most accurate theoretical electron affinities for (6)Li and (7)Li to date.
• Calculated EA for (7)Li as 4984.9842(30) cm⁻¹ and for (6)Li as 4984.9015(30) cm⁻¹.
• Determined the (7)Li/(6)Li EA isotope shift to be 0.0827 cm⁻¹.

Conclusions:

• The study provides benchmark theoretical values for lithium electron affinities.
• Explicitly including nuclear motion significantly enhances calculation accuracy.
• The precise EA values and isotope shift are vital for atomic spectroscopy and fundamental physics.