Structural properties and electron density of NaCl

The validity of all-electron total-energy local-density calculations for ionic insulators is investigated for NaCl using our full-potential linearized augmented-plane-wave method. We find that the experimental zero-temperature structural parameters are accurately described within the local-density approximation. Comparison of theoretical and experimental form factors shows large discrepancies for odd high-indexed reflections which is attributed to the procedure used to extract T=0 results from the room-temperature measurements. We conclude that a more stringent test of the charge density awaits the availability of more precise experimental form factors measured at low temperatures.