Published online by Cambridge University Press: 20 March 2020
We study the thermodynamic formalism of a $C^{\infty }$ non-uniformly hyperbolic diffeomorphism on the 2-torus, known as the Katok map. We prove for a Hölder continuous potential with one additional condition, or geometric
$t$-potential
$\unicode[STIX]{x1D711}_{t}$ with
$t<1$, the equilibrium state exists and is unique. We derive the level-2 large deviation principle for the equilibrium state of
$\unicode[STIX]{x1D711}_{t}$. We study the multifractal spectra of the Katok map for the entropy and dimension of level sets of Lyapunov exponents.