2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/27573It was a difficult problem to determine the Gaussian fixed line from the numerical data, because close to the Berezinskii-Kosterlitz-Thouless multicritical point the divergence of the correlation length becomes very slow. Considering the renormalization group behavior, we find an efficient method to determine the Gaussian fixed line.6 pages, latex2.09Condensed Mattertext