Extraction of a One-Particle Reduced Density Matrix from a Quantum Monte Carlo Electronic Density: A New Tool for Studying Nondynamic Correlation

In this work, we present a method to build first order reduced density matrix (1-RDM) of molecule from variational Quantum Monte Carlo (VMC) computations by means given correlated mapping wave function. Such function is modeled on Generalized Valence Bond plus Complete Active Space Self Configuration Interaction form and fits at best the resulting Slater-Jastrow VMC. The accuracy proposed has been proved comparing kinetic energy with corresponding VMC value. This 1-RDM used analyze amount correlation eventually captured in Kohn-Sham calculations performed an unrestricted approach (UKS-DFT) different functionals. We test selected set molecules that show significant multireference character. analysis, compared both local global indicators nondynamic dynamic correlation. Moreover, following natural orbital decomposition 1-RDM, also effective temperatures Fermi-like distributions. Although there general agreement between UKS-DFT VMC, found match functional LC-BLYP.