We perform a direct variational determination of the second-order (two-particle) density
matrix corresponding to a many-electron system, under a restricted set of the two-index N …

The one-particle reduced density matrix functional theory in its natural orbital functional
(NOF) version is used to study strongly correlated electrons. We show the ability of the Piris …

The variational reduced density matrix theory has been recently applied with great success
to models within the truncated doubly occupied configuration interaction space, which …

In this work, we formulate the equations of motion corresponding to the Hermitian operator
method in the framework of the doubly occupied configuration interaction space. The …

This work incorporates translational and reflection symmetry reductions to the variational
determination of the two-particle reduced density matrix (2-RDM) corresponding to the …

In this work, the Hellmann–Feynman theorem is extended within the doubly occupied
configuration interaction space to enable practical calculations of reduced density matrices …

We investigate an approach for studying the ground state of a quantum many-body
Hamiltonian that is based on treating the correlation functions as variational parameters. In …

Strong electron correlation in materials is explored within a class of model Hamiltonians that
treat only pair interactions between electrons. The model is unique among typical spin …

Minimizing the energy of an N N-electron system as a functional of a two-electron reduced
density matrix (2-RDM), constrained by necessary N N-representability conditions …

The reduced density matrix is variationally optimized for the two-dimensional Hubbard
model. Exploiting all symmetries present in the system, we have been able to study 6× 6 …