Integral-Direct Hartree-Fock and Møller-Plesset Perturbation Theory for Periodic Systems with Density Fitting:...

Area of Science:

• Computational Chemistry
• Materials Science

Background:

• Accurate electronic structure calculations are crucial for understanding material properties.
• Previous methods for periodic systems had significant storage limitations, restricting system size.

Purpose of the Study:

• To develop and implement efficient integral-direct, density-fitted Hartree-Fock (HF) and Møller-Plesset perturbation theory (MP2) methods for periodic systems.
• To enable the study of larger systems at the MP2 level, overcoming previous computational bottlenecks.

Main Methods:

• Integral-direct, density-fitted algorithms for HF and MP2 calculations.
• Application to the benzene crystal in thermodynamic and complete basis set limits.

Main Results:

• A new code that significantly reduces storage requirements, allowing for calculations on systems an order of magnitude larger.
• Prediction of a benzene crystal MP2 cohesive energy of -72.8 kJ/mol, which is more accurate than previous calculations.
• Demonstration that modified MP2 models approach chemical accuracy for molecular crystal cohesive energies.

Conclusions:

• The developed computational methods are efficient and scalable for periodic systems.
• These methods provide accurate cohesive energies for molecular crystals, approaching chemical accuracy.
• The new approach offers a promising, cost-effective alternative for future studies on molecular crystals.