Low-temperature expansion of the free energy in the ASOS model Original Research Article

We calculate the low-temperature series of the free energy in the absolute-value solid-on-solid (ASOS) model to order u23 using the finite-lattice method. The property of the obtained series and the behavior of their Padé approximants confirms us that the roughening transition in the ASOS model is of the Kosterlitz-Thouless type.