Graphics Processing Unit-Accelerated Density-Fitting Coupled-Cluster and Equation-of-Motion Coupled-Cluster Methods...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Accurate electronic structure calculations are crucial for understanding heavy-element systems.
• Spin-orbit coupling (SOC) significantly influences the properties of heavy elements.
• Existing computational methods for SOC can be resource-intensive.

Purpose of the Study:

• To develop efficient coupled-cluster (CC) programs incorporating spin-orbit coupling (SOC) within the density-fitting (DF) approximation.
• To enable accurate and computationally feasible electronic structure calculations for heavy-element systems.

Main Methods:

• Implementation of density-fitting spin-orbit coupling (DF-SOC) in coupled-cluster (CC) methods: DF-SOC-CCSD, DF-SOC-CCSD(T), and DF-SOC-EOM-EE-CCSD.
• Utilizing a spin-independent formulation for simplified code and graphics processing unit (GPU) acceleration.
• Incorporating spatial symmetry and single/double precision for enhanced computational efficiency.

Main Results:

• The DF approximation introduces negligible errors in calculations involving SOC.
• Accurate SOC splittings are maintained even with single-precision arithmetic.
• GPU acceleration demonstrates good scalability, achieving over 5-fold speedup for larger systems.

Conclusions:

• The developed DF-SOC-CC program suite offers an accurate and efficient approach for electronic structure calculations of heavy-element systems.
• The methods effectively handle the complexities of SOC in heavy elements.
• The computational efficiency is significantly improved through DF approximation and GPU acceleration.