Results of Rietveld refinement for indium nitride data collected in the temperature range 105–295 K are presented. Acicular microcrystals of indium nitride prepared by reaction of liquid indium with nitrogen plasma were studied by X-ray diffraction. The diffraction measurements were carried out at the Swiss-Norwegian Beamline SNBL (ESRF) using a MAR345 image-plate detector. Excellent counting statistics allowed for refinement of the lattice parameters of InN as well as those of the metallic indium secondary phase. In the studied temperature range, the InN lattice parameters show a smooth increase that can be approximated by a linear function. Lattice-parameter dependencies confirm the trends indicated earlier by data measured using a conventional equipment. The relative change of both the a and c lattice parameters with increasing the temperature in the studied range is about 0.05%. The axial ratio slightly decreases with rising temperature. The experimental value of the free structural parameter, u =0.3769(14), is reported for InN for the first time. Its temperature variation is found to be considerably smaller than the experimental error. The thermal-expansion coefficients (TECs), derived from the linearly approximated lattice-parameter dependencies, are α _a =3.09(14)×10 ⁻⁶ K ⁻¹ and α _c =2.79(16)×10 ⁻⁶ K ⁻¹ . The evaluated TECs are generally consistent with the earlier data. For the present dataset, the accuracy is apparently higher for both, the lattice parameters and thermal-expansion coefficients, than for the earlier results. The refined lattice parameter c _In of the indium secondary phase exhibits the known strongly nonlinear behavior; a shift (Δ T equal about −50 K) of the maximum in c _In ( T ) dependence is observed with respect to the literature data.

It is proved that in slab simulations of uniform semiconductor surfaces the electric field in the vacuum space should vanish. In standard approach this condition was achieved by introduction of the dipole correction [J. Neugebauer and M. Scheffler, Phys. Rev. B 46, 16067 (1992)]. An effective and stable method of exact solution of Poisson equation, based on Laplace correction, which attains the zero field condition in the vacuum, is described. The dipole correction to the slab energy is removed. Additionally, a method of the control of electric field within the slab is introduced, applicable in direct simulations of Fermi level influence on the properties of semiconductor surfaces.