@article{oai:niigata-u.repo.nii.ac.jp:00002503, author = {Sano, K. and Ono, Y.}, journal = {Physical review. Third series. B, Condensed matter and materials physics, Physical review. Third series. B, Condensed matter and materials physics}, month = {Mar}, note = {We propose a different combined approach, which consists of the exact diagonalization, renormalization group, and Bethe ansatz methods, for precise estimates of the charge gap Δ in the one-dimensional extended Hubbard model, with on-site and nearest-neighbor interactions U and V at quarter filling. This approach enables us to obtain the absolute value of Δ, including the prefactor, without ambiguity even in the critical regime of the metal-insulator transition (MIT) where Δ is exponentially small, beyond usual renormalization group methods and/or finite-size scaling approaches. The detailed results of Δ, down to the order of 10−10 near the MIT, are shown as contour lines on the U-V plane.}, pages = {113103-1--113103-4}, title = {Charge gap in the one-dimensional extended Hubbard model at quarter filling}, volume = {75}, year = {2007} }