Variational Determination Of Ground And Excited-State Two-Electron Reduced Density Matrices In The Doubly Occupied Configuration Space: A Dispersion Operator Approach

D.R. ALCOBA; O.B. OÑA; L. LAIN; A. TORRE; P. CAPUZZI; G.E. MASSACCESI; E. RIOS; A. RUBIO-GARCIA; J. DUKELSKY

JOURNAL OF CHEMICAL PHYSICS

AMER INST PHYSICS

Lugar: New York; Año: 2021 vol. 154 p. 224104 - 224104

0021-9606

This work implements a variational determination of the elements of two-electron reduced density matrices corresponding to the ground and excited states of N-electron interacting systems based on the dispersion operator technique. The procedure extends the previously reported proposal [Nakata et al., J. Chem. Phys. 125, 244109 (2006)] to two-particle interaction Hamiltonians and N-representability conditions for the two-, three-, and four-particle reduced density matrices in the doubly occupied configuration interaction space. The treatment has been applied to describe electronic spectra using two benchmark exactly solvable pairing models: reduced Bardeen?Cooper?Schrieffer and Richardson?Gaudin?Kitaev Hamiltonians. The dispersion operator combined with N-representability conditions up to the four-particle reduced density matrices provides excellent results.