We present an innovative cluster-based method employing linear combinations of diverse
cluster mean-field states and apply it to describe the ground state of strongly correlated spin …

The two‐electron reduced density matrix (2RDM) carries enough information to evaluate the
electronic energy of a many‐electron system. The variational 2RDM (v2RDM) approach …

We introduce S z spin-projection based on cluster mean-field theory and apply it to the
ground state of strongly correlated spin systems. In cluster mean-fields, the ground state …

The N-representability problem consists in determining whether, for a given p-body matrix,
there exists at least one N-body density matrix from which the p-body matrix can be obtained …

The bootstrap method aims to solve problems by imposing constraints on the space of
physical observables, which often follow from physical assumptions such as positivity and …

The Jordan–Wigner transformation permits one to convert spin 1/2 operators into spinless
fermion ones, or vice versa. In some cases, it transforms an interacting spin Hamiltonian into …

El problema cuántico de muchos cuerpos presenta, en general, complejidad exponencial
en la dimensión del sistema. Esta complejidad implica que, eventualmente, sea prohibitivo …

The thesis commences with an initial chapter serving as an introduction, offering readers the
essential groundwork and prior investigations that paved the way for this research. It is …

Open quantum systems are ubiquitous in nature, as it is often impossible to completely
decouple a system under study from its environment. While the effects of this coupling are, in …