  A one-dimensional non-iterative direct method was employed for normalized
crystal truncation rod. The non-iterative approach, utilizing Kramers-Kronig
relation, avoids the ambiguities due to the improper initial model or the
incomplete convergence in the conventional iterative methods. The validity and
limitation of the present method are demonstrated through both numerical
simulations and experiments with Pt (111) in 0.1 M CsF aqueous solution. The
present method is compared to conventional iterative phase-retrieval methods.
