Electron correlation effects and spin-liquid state in the Herbertsmithite Kagome lattice

We employ real-space variational quantum Monte Carlo methods with resonating valence bond many-body wave functions to investigate electron correlation effects in the Kagome system Zn_xCu4-xO₆. Using three trial wave functions of the Slater-Jastrow type, where (i) only the Jastrow correlation factor is optimized and the orbitals obtained by density functional theory, (ii) both the Jastrow factor and the Slater determinant are optimized, and (iii) additionally the Slater determinant is substituted by an antisymmetrized-geminal power wave function, we analyze static and dynamic correlation energies across concentrations x=0, frac{1}{3}, frac{2}{3}, 1. Our results show that the correlation energy increases with the concentration of Zn_x. Optimizing the Slater determinant significantly enhances the correlation energy by approximately sim -73(4) mHa per electron. Eventually, the emergence of a quantum spin liquid state driven by a long-range correlation energy is discussed.