On the application of maximum entropy method to the electron density distribution and phaseless problem

The application of Maximum Entropy Method to the electron density reconstru ction in the case of phaseless problem in both centro- and non-centrosymmet ric structures is described. The use of specially constructed priors is sug gested for a simultaneous refinement of the electron density distribution a nd phases of the observed structure factors. On an example of GaN data it i s shown that a non-uniform prior may be a necessity for arriving at proper reconstruction of the charge density distributions. MEM can be also very se nsitive to the positional parameters as demonstrated on the case of FeSi. T he use of non-uniform prior helps also to understand the origin of covalent bonding, which is demonstrated on the Si case, for which obtained charge d ensity distribution is in excellent agreement with theoretical predictions.