arXiv:1604.00948 · Physical review. E
Finite-size corrections to scaling of the magnetization distribution in the two-dimensional XY model at zero temperature
Guillermo Palma, Ferenc Niedermayer A, Zoltàn Ràcz, A. Riveros, D. Zambrano
Abstract
The zero-temperature, classical $XY$ model on an $L\ifmmode\times\else\texttimes\fi{}L$ square lattice is studied by exploring the distribution ${\mathrm{\ensuremath{\Phi}}}_{L}(y)$ of its centered and normalized magnetization $y$ in the large-$L$ limit. An integral representation of the cumulant generating function, known from earlier works, is used for the numerical evaluation of ${\mathrm{\ensuremath{\Phi}}}_{L}(y)$, and the limit distribution ${\mathrm{\ensuremath{\Phi}}}_{L\ensuremath{\rightarrow}\ensuremath{\infty}}(y)={\mathrm{\ensuremath{\Phi}}}_{0}(y)$ is obtained with high precision. The two leading finite-size corrections ${\mathrm{\ensuremath{\Phi}}}_{L}(y)\ensuremath{-}{\mathrm{\ensuremath{\Phi}}}_{0}(y)\ensuremath{\approx}{a}_{1}(L)\phantom{\rule{0.16em}{0ex}}{\mathrm{\ensuremath{\Phi}}}_{1}(y)+{a}_{2}(L)\phantom{\rule{0.16em}{0ex}}{\mathrm{\ensuremath{\Phi}}}_{2}(y)$ are also extracted both from numerics and from analytic calculations. We find that the amplitude ${a}_{1}(L)$ scales as $ln(L/{L}_{0})/{L}^{2}$ and the shape correction function ${\mathrm{\ensuremath{\Phi}}}_{1}(y)$ can be expressed through the low-order derivatives of the limit distribution, ${\mathrm{\ensuremath{\Phi}}}_{1}(y)={[\phantom{\rule{0.16em}{0ex}}y\phantom{\rule{0.16em}{0ex}}{\mathrm{\ensuremath{\Phi}}}_{0}(y)+{\mathrm{\ensuremath{\Phi}}}_{0}^{\ensuremath{'}}(y)\phantom{\rule{0.16em}{0ex}}]}^{\ensuremath{'}}$. Thus, ${\mathrm{\ensuremath{\Phi}}}_{1}(y)$ carries the same universal features as the limit distribution and can be used for consistency checks of universality claims based on finite-size systems. The second finite-size correction has an amplitude ${a}_{2}(L)\ensuremath{\propto}1/{L}^{2}$ and one finds that ${a}_{2}\phantom{\rule{0.16em}{0ex}}{\mathrm{\ensuremath{\Phi}}}_{2}(y)\ensuremath{\ll}{a}_{1}\phantom{\rule{0.16em}{0ex}}{\mathrm{\ensuremath{\Phi}}}_{1}(y)$ already for small system size ($L>10$). We illustrate the feasibility of observing the calculated finite-size corrections by performing simulations of the $XY$ model at low temperatures, including $T=0$.