Space-analyticity of wave function under evolution with Coulomb potential

Free evolution conserves analyticity but what if the initial state $\Psi_0$ is real-analytic but the acting Hamiltonian includes a non-analytic or even singular potential, like the Coulomb central potential $V(x) = -1/|x|$? One would suppose that in this case, analyticity gets destroyed, at least for almost all times $t \neq 0$.

If one scans the literature a positive analyticity result can be found in [1] for analytic potentials in one space dimension. Counter-examples where analyticity is lost when potentials are not that nice are hard to find, there is a statement of yuggib on StackExchange Physics that evolution with a Coulomb potential already kills continuous differentiability, but without reference or proof. And there is Theorem 1.2 in [2] that states that the fundamental solution to the time-dependent Schrödinger equation is nowhere $\mathcal{C}^1$ for a certain class of potentials. But this class does not include Coulomb potentials and the properties of the fundamental solution do not necessarily carry over to the solution itself. In [3] we read:

On the other hand, if $V$ is not smooth, e.g., if $V$ is the Coulomb potential in dimension three, the singularities of $V$ create those of the FDS and $E(t, x, y)$ [the fundamental solution] is not smooth everywhere. However, the strong dissipation property of the free propagator $\mathrm{e}^{-\mathrm{itH_0}}$ moderates the singularities and we expect that $E(t, x, y)$ is bounded and continuous for $t\neq 0$ if $V$ is bounded at infinity in a suitable norm and is not too singular locally (see Simon [14] [ref. [4]] who conjectures that this is true if $V$ is of Kato class).

The author goes on and shows boundedness and continuity for the fundamental solution for a class that includes the Coulomb potential in dimension three. Finally one should note that for a Hamiltonian with Coulomb potentials and even including Coulomb interactions between multiple particles, it is known that an eigenstate is analytic away from the potential sigularities and has $|x|$-formed cusps at the location of the singularities [5].


1. a Nakao Hayashi, Saburou Saitoh, 1990. Analyticity and smoothing effect for the Schrödinger equation. Annales de l'IHP Physique théorique, pp.163–173.
2. a Kenji Yajima, 1996. Smoothness and non-smoothness of the fundamental solution of time dependent Schrödinger equations. Communications in mathematical physics, 181, Springer, pp.605–629.
3. a Kenji Yajima, 1998. Boundedness and continuity of the fundamental solution of the time dependent Schrodinger equation with singular potentials. Tohoku Mathematical Journal, Second Series, 50, Mathematical Institute, Tohoku University, pp.577–595.
5. a Søren Fournais, Maria Hoffmann-Ostenhof, Thomas Hoffmann-Ostenhof, Thomas Østergaard Sørensen, 2009. Analytic structure of many-body Coulombic wave functions. Communications in Mathematical Physics, 289, Springer, pp.291–310.