The R\'{ e}nyi statistics is applied for a description of finite size effects in the 1D Ising model. We calculate the internal energy of the spin chain and the system temperature using the R\'{ e}nyi distribution and postulate them to be equal to their counterparts, obtained in the microcanonical ensemble. It allows us to self-consistently derive the R\'{ e}nyi $q$-index and the Lagrange parameter $T$ to relate them to the physically observed system temperature $T_{ \rm ph}$, and to show that the entropic phase transitions are possible in a broad temperature domain. We have also studied the temperature dependence of the internal energy $U(T_{ \rm ph})$ at constant $q$ and an influence of the size related effects on the system thermodynamics.
Categories: cond-mat.stat-mech