Decoupled-Cell Quantum Monte Carlo: How Should We Calculate the Energy?
An alternative and more general method for calculating the energy in a Decoupled Cell Monte Carlo simulation is presented. Examining this method on the one-dimensional XY model, the energy calculated from the cell energies is found to be well behaved in the low temperature limit, unlike the traditional energy calculation based on spin-spin correlations. In addition, the cell energies scale with the cell size, and thus can be extrapolated to infinite cell size to further remove errors arising from the finite size of the cell in the Monte Carlo.
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