1971/10/28 by P. Pfeuty, P Pfeuty, R. J. Elliott +1 · 2 citations
Physics and Astronomy · #Opinion Dynamics and Social Influence #Quantum many-body systems #Theoretical and Computational Physics
paper · doi:10.1088/0022-3719/4/15/024
crossref issued 1971/10/28 · crossref published 1971/10/28 · crossref published-print 1971/10/28 · openalex publication_date 1971/10/28 · crossref published-online 2001/03/14 · crossref created 2002/07/26 · crossref deposited 2020/04/10 · openalex created_date 2025/10/10 · crossref indexed 2026/07/27 · openalex updated_date 2026/07/30
For Pt. I see ibid., vol. 4, 2359 (1971). The properties of the Ising model with a transverse field, with the Hamiltonian written H=- Gamma Sigma i S i x - 1 / 2 Sigma i,j J ij S i z S j z , are studied by perturbation expansions at T=0 in the ground state, both below and above the critical field Gamma C , for an hypercubic lattice and short range interactions. The order parameter (S z ) and the correlation function G=) Sigma i S i z Sigma j S j z ) are calculated respectively below and above Gamma C . The gap in the excitation spectrum is also studied above the critical field. The critical behaviour obtained from these expansions at T=0 is different from that obtained at T finite and is shown to be analogous to the critical behaviour of the Ising model for a lattice with one more dimension.