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Please use this identifier to cite or link to this item: https://dspace.lboro.ac.uk/2134/1227

Title: Exact classical effective potentials
Authors: Samson, J.H.
Keywords: Quantum physics
Statistical mechanics
Issue Date: 1999
Abstract: A quantum spin system can be modelled by an equivalent classical system, with an effective Hamiltonian obtained by integrating all non-zero frequency modes out of the path integral. The effective Hamiltonian H_eff(S_i) derived from the coherent-state integral is highly singular: the quasiprobability density exp(-beta H_eff), a Wigner function, imposes quantisation through derivatives of delta functions. This quasiprobability is the distribution of the time-averaged lower symbol of the spin in the coherent-state integral. We relate the quantum Monte Carlo minus-sign problem to the non-positivity of this quasiprobability, both analytically and by Monte Carlo integration.
Description: This is a pre-print. It is also available at: http://arxiv.org/abs/quant-ph/9905089.
URI: https://dspace.lboro.ac.uk/2134/1227
Appears in Collections:Pre-Prints (Physics)

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