Density-fitting tools

This module contains various utils for density fitting.

generate_3idx_integrals(EC::ECInfo, cMO::SpinMatrix, fitbasis="mpfit"; save3idx=true)

Generate $v_p^{qL}$ with $v_{pr}^{qs} = v_p^{qL} δ_{LL'} v_r^{sL'}$ and store in file mmL. If save3idx is false, no 3-index integrals are calculated, only save pseudo-square-root-inverse Cholesky decomposition.

generate_AO_DF_integrals(EC::ECInfo, fitbasis="mpfit"; save3idx=true)

Generate AO integrals using DF + Cholesky. If save3idx is true, save Cholesky-decomposed 3-index integrals, otherwise save pseudo-square-root-inverse Cholesky decomposition.

Return nuclear repulsion energy.

generate_DF_Fock(EC::ECInfo, cMO::SpinMatrix; check_diagonal=false)

Generate DF Fock matrix in MO basis. If check_diagonal is true, check the off-diagonal elements of the Fock matrix to be small. The Fock matrix is saved in files f_mm/f_MM and orbital energies in e_m/e_M.

Return reference energy.

generate_DF_integrals(EC::ECInfo, cMO::SpinMatrix; save3idx=true)

Generate $v_p^{qL}$ and $f_p^q$ with $v_{pr}^{qs} = v_p^{qL} δ_{LL'} v_r^{sL'}$. The $v_p^{qL}$ are generated using mpfit fitting basis, and the $f_p^q$ are generated using jkfit fitting basis. The integrals are stored in files mmL and f_mm.

Return reference energy (calculated using jkfit fitting basis).