electronic structure by quantum Monte Carlo*

The alpha phase of RuCl₃ crystal consists of 2D stacked honeycomb layers coupled with van der Waals interactions. Both bulk and multi/single layers of bonded RuCl₆ octahedra have been produced and exhibit several promising electronic, magnetic and structural properties. The ground state is a magnetic insulator with several possible magnetic states that are energetically very close. Furthermore, the material allows for a formation of putative spin liquid phases and other unconventional magnetic states due to Ru spin-orbit coupling and favorable orbital occupations. We study these systems using fixed-node quantum Monte Carlo (QMC) with averaged spin-orbit as well as with recently developed fixed-phase spin-orbit QMC that is based on two-component spinors formalism. In particular, we attempt to understand the role of electron correlations as they affect the ground and excited states. We carry out calculations for the low-lying magnetic states vs non-magnetic state and attempt to reveal the impact of explicit spin-orbit effects on magnetic and electronic properties.