Elongation cutoff technique: low-order scaling SCF method.

Area of Science:

• Computational chemistry
• Quantum chemistry
• Theoretical chemistry

Background:

• Conventional Hartree-Fock (HF) calculations with two-electron integrals (TEI) stored on disk face scalability challenges with increasing system size.
• Extending these calculations to larger systems requires more efficient computational methods.

Purpose of the Study:

• To introduce and evaluate the elongation cutoff technique for restricted Hartree-Fock (HF) calculations.
• To assess the computational efficiency and scalability of this new method compared to conventional approaches.

Main Methods:

• The elongation cutoff technique was applied to two model systems at the restricted Hartree-Fock (HF) level of theory.
• Calculations involved storing two-electron integrals (TEI) on disk.
• The impact of an 'interaction radius' was investigated to achieve linear scaling.

Main Results:

• The number of TEI in elongation cutoff calculations scales linearly with system size, enabling calculations on larger systems.
• Step CPU time in elongation cutoff calculations is significantly lower than in conventional HF calculations.
• Total CPU time is reduced by approximately 40% compared to conventional HF, or is comparable to direct calculations using the quantum fast multipoles method.
• Introducing an interaction radius allows for linear scaling in self-consistent field (SCF) calculations.

Conclusions:

• The elongation cutoff technique offers a significant computational advantage for large-scale quantum chemistry simulations.
• This method effectively reduces computational cost and improves scalability for HF and SCF calculations.
• The technique shows promise for extending the applicability of conventional computational chemistry methods to larger molecular systems.