Electron momentum distribution in SnS

A study of electron momentum density distribution in SnS by means of Compton profiles is presented. The measurement on polycrystalline sample of SnS is performed employing 59.54 keV gamma‐rays emanating from an Am241 radioisotope. The calculations are performed on the basis of density‐functional theory based ab‐initio linear combination of atomic orbitals method embodied in the CRYSTAL program. The correlation scheme proposed by von Barth and Hedin is adopted. The generalized gradient approximation proposed by Perdew and Wang is also considered to treat the correlation. The exchange is treated following the Becke scheme. Both the correlation schemes are in good agreement with the measurement. The better agreement with experimental result is, however, observed with the von Barth and Hedin correlation that also gives lower ground‐state energy than the Perdew–Wang generalized gradient approximation. Ionic model calculations for a number of configurations of Sn+xS−x (0.0 ≤ x ≤ 2) are also performed utilizing free‐atom profiles. The ionic model suggests transfer of 2.0 electrons from the valence 5p state of Sn to the 3p state of S.