Van Meer R., Gritsenko O., Chai J.-D.Gritsenko O., Chai J.-D.Van Meer R.JENG-DA CHAI2021-07-282021-07-28202024699926https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092561302&doi=10.1103%2fPhysRevA.102.032815&partnerID=40&md5=7f59b82db77df80a8f447f63f0d01b1ahttps://scholars.lib.ntu.edu.tw/handle/123456789/573493A combined density and density-matrix functional method is proposed for the calculation of potential energy curves of molecular multibond dissociation. Its density-matrix part, a pair-density functional, efficiently approximates the ab initio pair density of the complete active space (CAS) method. The corresponding approximate on-top pair density Π is employed to correct for double counting in the correlation energy functional. The proposed ELS+ method, which augments the extended L?wdin-Shull (ELS) density-matrix functional with the Π-based scaled density functional, closely reproduces potential curves of the paradigmatic multibond dissociation in N2, H2O, and H2CO molecules calculated with the recently proposed CASΠDFT [CAS augmented with the Π-based scaled correlation correction of density functional theory (DFT)] method. Furthermore, with the additional correction for the intrafragment correlation between the broken-bond electrons, ELS++ reproduces well the benchmark potential curve of the N2 molecule by Lie and Clementi. ? 2020 American Physical Society.Calculations; Curve fitting; Dissociation; Molecules; Potential energy; Quantum theory; Complete active space; Correlation corrections; Correlation energy; Density functionals; Dynamical correlations; Potential energy curves; Reduced-density matrix; Strong correlation; Density functional theoryjournal article10.1103/PhysRevA.102.0328152-s2.0-85092561302