Accurate and Efficient Spin-Phonon Coupling and Spin Dynamics Calculations for Molecular Solids

Area of Science:

• Molecular materials science
• Quantum computing and optoelectronics
• Computational chemistry

Background:

• Spin-phonon coupling is critical for energy transfer in molecular materials, influencing intersystem crossing, quantum decoherence, and magnetic relaxation.
• Accurate theoretical prediction of spin-phonon coupling and spin dynamics in condensed phases is essential for advancing molecular technologies.

Purpose of the Study:

• To demonstrate the accuracy of *ab initio* methods for calculating spin-phonon coupling in molecular solids.
• To investigate the spin dynamics of a single-molecule magnet through quantitative comparison with experimental results.
• To establish the validity of the Born-Markov assumption in spin dynamics calculations for molecular magnets.

Main Methods:

• Utilized recent advancements in analytic spin-phonon coupling calculations.
• Incorporated a novel method for including infinite electrostatic potential in computations.
• Performed the first *ab initio* determination of phonon lifetimes and line widths for a molecular magnet.

Main Results:

• Achieved quantitative agreement between *ab initio* calculations and experimental data for a single-molecule magnet.
• Demonstrated the validity of the Born-Markov assumption for spin dynamics, even without exact phonon line widths.
• Developed open-source packages to facilitate cost-effective and accurate spin-phonon coupling calculations.

Conclusions:

• *Ab initio* methods are mature for calculating spin-phonon coupling and spin dynamics in molecular solids.
• The developed computational approach enables exploration of spin dynamics origins and quantitative experimental validation.
• Open-source tools make accurate spin-phonon coupling calculations accessible for molecular materials research.