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arXiv · 2603.14808

Study of the triangular-lattice Hubbard model with constrained-path quantum Monte Carlo

Shu Fay Ung·Ankit Mahajan·David R. Reichman
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Abstract

We benchmark constrained-path Monte Carlo (CPMC) on the triangular-lattice Hubbard model for several fillings and $U$ values and show that symmetry-adapted trial wave functions substantially improve quantitative accuracy. Away from half-filling, simple free-electron-based trials that preserve the ground state symmetry yield energy deviations $\lesssim 1\%$ from exact diagonalization and density matrix renormalization group results. At half-filling, strong frustration in the intermediate to large $U$ regimes necessitates symmetry-projected trials to reach comparable accuracy, where both free-electron and symmetry-broken Hartree-Fock trials incur substantial constraint bias. Since the computational cost of CPMC with symmetry projection scales polynomially with system size, our results motivate its use as a practical route for studying competing ground states in strongly correlated, frustrated systems.

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Shu Fay Ung, Ankit Mahajan, David R. Reichman. 2026-03-16. Study of the triangular-lattice Hubbard model with constrained-path quantum Monte Carlo. https://doi.org/10.1103/j85h-z664

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