Electrostatic potential of ferroelectric PbTiO3:: Visualized electron polarization of Pb ion

A different method is proposed to evaluate the electrostatic potential and electric field from x-ray diffraction data by using maximum entropy method. The efficiency of the method is revealed in the application to a ferroelectric material PbTiO3. Visualized electrostatic potential and electric field on the charge density distribution give a direct evidence for the dipolar polarization of the Pb ion. They show close agreement with results by ab initio calculations.