Quantum eigenfunctions in terms of periodic orbits of chaotic systems

A resummed formula for the Wigner function, corresponding to an eigenfunction of a chaotic system, in terms of periodic orbits, is developed. The infinite sum over periodic orbits is effectively truncated with the help of an extension of a method that was applied to the spectral determinant by Berry and Keating (1992). In principle, the formula enables the computation of eigenstates and the probability density of wavefunctions from classical periodic orbits. The conditions for appearance of 'scars' are discussed.