Linear Scaling Property of Fock Matrix, Molecular Orbitals, and Performance of Conventional Hartree–Fock Method in Ab initio Molecular Calculations

The investigation of the scaling properties of the Fock matrix, and molecular orbitals shows that they linearly scale with respect to the number of basis functions for large molecular systems. It has been shown that only small number of largest matrix elements of the Fock matrix are important for calculation of the total molecular energy with high precision. Thus, the main quantities of the Hartree–Fock method, namely one- and two-electron integrals, Fock matrix, molecular orbitals, and density matrix possess the linear scaling properties. Additionally, performance of the modified conventional SCF method with calculation of Fock matrix from two-electron integrals stored with using data compression technique and density difference prescreening proposed recently has been investigated.