Multi-Level Coupled-Cluster Description of Crystal Lattice Energies

Area of Science:

• Computational chemistry
• Quantum chemistry
• Materials science

Background:

• The many-body expansion (MBE) is crucial for ab initio calculations of molecular solids.
• Efficient computation of n-body contributions in MBE is a significant challenge.

Purpose of the Study:

• To develop a practical and efficient multi-level coupled-cluster approach for MBE.
• To achieve chemical accuracy in ab initio lattice energy calculations for molecular solids.

Main Methods:

• Employed a multi-level coupled-cluster (CC) strategy adapting approximation levels by interaction type and distance.
• Utilized high-level CC for local interactions and random-phase approximation (RPA) for long-range interactions.
• Incorporated an RPA energy correction and periodic Hartree-Fock correction for accelerated convergence.

Main Results:

• The developed method achieved a mean absolute error of 3.1 kJ/mol on the X23 dataset.
• Demonstrated chemical accuracy for absolute lattice energies compared to diffusion Monte Carlo data.

Conclusions:

• The proposed multi-level CC approach significantly enhances the efficiency of MBE for molecular solids.
• This method provides a reliable and accurate tool for ab initio studies of condensed matter systems.