Analysis of the MgO structure factors

The results of recent measurements [Zuo et al., Phys. Rev. Lett. 78, 4777 (1997)] of some low-order structure factors of MgO have been reinterpreted by means of an ab initio calculation and of two models of charge density. The discrepancies between the calculated and the experimental structure factors are 3% for the 111 reflection and smaller than 1% in the other cases. The charge transfer, which is well defined in the framework of the ab initio method that we have used, is found to be equal to 2. On the other hand, refinements of the model parameters yield values of the charge transfer ranging from 1.81 to 1.92, with little change on the R factor. The electron density of the oxygen ion in the crystal has also been deduced from the model analysis of the experimental data. The resulting distribution is in excellent agreement with that obtained by the ab initio calculation. These conclusions differ from those of the preceding analysis of the same experimental data performed by Zuo et al. [S0163-1829(99)02436-4].